Second Physics Notes

8/12/2019 Second Physics Notes

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PHYSICS NOTES

CL SS X

CHAPTER NO.1 INTRODUCTION TO PHYSICS

DEFINITION OF PHYSICS

The science of the nature. Physics is that branch of science which treats of laws andproperties of matter and force acting upon it. The department of natural science (Physics)which treats the causes (Electricity, Head, Light, Magnetism) that modifying the generalproperties of body natural philosophy.

OR

Physics is an important branch of !cience which offers the study of matter and energyalong with the interaction between them.

BRANCHES OF PHYSICS

There are many branches of physics"

1. ELECTRONICS

#$t is the branch of Physics which deals with de%elopment of electrons, emitting thede%ices and utili&ation and controlling of electrons flow in electrical circuit designed for%arious purposes.#

2 KINEMETICS

#$t is the branch of Physics which deals with description of motion without reference toany opposing or e'ternal force#.

3. OPTICS

#$t is the branch of Physics which deals with light and its properties.

4. DYNAMICS

#$t is the branch of Physics which deals with causes of motion and their effects#

5. CALORIMETERY

#$t is the branch of Physics which deals with measurement of heat#.

6. ATOMIC PHYSICS

#$t is the branch of Physics which deals with properties and structure of tom#.

7. MECHANICS

#$t is the branch of Physics which deals with motion of particles or bodies under theaction of gi%en force#.

COMPOSED BY UBEDULLAH MEMON Page 1


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CONTRIBUTION OF MUSLIMS SCIENTISTS

1. IBNE-AL-HAITHAM (965-1 39 A.D!

INTRODUCTION

He was born in asra a city of $ra*. He was one of the great Muslim !cientist. He was afeat scholar of physics, mathematics, engineering+, astronomy and medicine.

CONTRIBUTION

1. He was a first man who discussed in detail about the luminous, non luminous andtransparent bodies.

2. He also ga%e the structure and wor-ing of eyes.

3. He ga%e us many laws of reflection and wrote many boo-s about the reflection of light.

4. He also first time ga%e the idea that whene%er the ray of light is incident on an ob ectsome of the incident rays are reflected from the ob ect and enter the eyesconse*uently the ob ect becomes %isible to the eyes which is accepted the scientific%iew.

2. AL-BERUNI

INTRODUCTION

He was born in erun a small town of fghanistan. He wrote many boo-s on %arioussub ects li-e physics, mathematics, culture, astronomy e.t.c

CONTRIBUTION

1. He discussed in detail about the mo%ement of sun moon and others planets .

2. He determined the densities of %arious metals .

3. He ga%e an idea that Earth is floating in the s-y li-e a ships in the water.

4. He also awarded that he was a first who said that the %elocity of light is more than the%elocity of sound.

3. MUHAMMAD IBNE MUSA KHA"R#MI

INTRODUCTION

bu bdullah Muhammad $bn Musa al /hwari&mi was born in 012 .3 at /hwari&m(/he%a), a town south of ri%er 4'us in present 5&be-istan.

CONTRIBUTION

1. l /hwari&mi was one of the greatest mathematicians e%er li%ed. He was the founderof se%eral branches and basic concepts of mathematics. He is also famous as anastronomer and geographer.

2. He de%eloped in detail trigonometric tables containing the sine functions, which werelater e'trapolated to tangent functions.

3. l /hwari&mi also de%eloped the calculus of two errors, which led him to the concept ofdifferentiation. He also refined the geometric representation of conic sections.

4. l /hwari&mi wrote a boo- on astronomical tables. !e%eral of his boo-s weretranslated into Latin in the early l6th century by delard of ath and 7erard of8remona. The treatises on rithmetic, /itab al 9am:a wal Tafree* bil Hisab al Hindi,and the one on lgebra, l Ma*ala fi Hisab al 9abr wa al Mu*abilah, are -nown onlyfrom Latin translations.

5. He was a first man who introduce the decimal system in mathematics.



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CHAPTER NO. 2 MEASUREMENTSDEFINITIONS

1. M$%$&

The length of the path tra%eled by light in %acuum in ;=6,?10 of a second is-nown as meter.

Length is a fundamental unit used for measurements of length, distance and height. $tis e*ual to the distance between two mar-s on a Platinum $ridium bar -ept at 2 8 in$nternational ureau of @eight and Measurements ($ @M) near Paris.

2. KILO'RAM

The mass of a Platinum $ridium cylinder -ept at 2 8 in $nternational ureau of @eight

and Measurements ($ @M) near Paris is considered to be ; -ilogram./ilogram is a fundamental unit used for measurements of mass.

3. SECOND

$t is e*ual to the duration of =,;=6,AB;,>>2 periods of radiation of 8esium ;BB inground state.

FUNDAMENTAL UNITS The international system of units is based on se%en independent units -nown asCundamental or asic 5nits. These are gi%en below";. M$%$& ( !) length, distance, height (l)6. K*+, & (/ !) mass (m)B. S$0, ( !) time (t)?. A $&$ (A!) electric current ($)1. K$+ * (K!) temperature (T)A. M,+$ ( ,+!) amount of substance (n)>. C $+ (0 !) luminous intensity ($%)

DERI ED UNITS

The units that re*uire two or more basic measurements of same units or different

fundamental units for its definition are called deri%ed units.;. S 8 &$ $%$& ( 2!) area ( )6. C8 *0 $%$& ( 3!) %olume (D)B. H$&%: (H:!) fre*uency (%)?. K*+, & $& 08 *0 $%$& (/ ; 3!) mass density (p)1. M$%$& $& $0, ; ) speed %elocity (D)A. R * $& $0, (& ; !) angular %elocity (w)>. M$%$& $& $0, 8 &$ ( ; 2!) acceleration (a)0. N$


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;B. ,+% ( ! (";A!) potential difference (D), electromoti%e force (E);?. O> (O $ !) electric resistance (F);1. F & (F!(A. ; !) capacitance (8);A. "$ $& (" !( . !) magnetic flu' (G);>. H$ &? (H! ( . ;A!) inductance (E);0. ,+% $& $%$& ( ; !) electric field strength (E);=. N$


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CHAPTER NO.3 SCALAR AND ECTOR UANTITIES

SCALAR

#!calar *uantity are those physical *uantity which are completely specified by theirmagnitude e'press with suitable unit. They do not re*uire any mention of the direction forcomplete their specificaton is called scalar *uantity.#

OR

# !calar *uantity are those physical *uantity which re*uire magnitude , e'press withsuitable unit only is called scalar *uantity.#

CHARACTERISTICS OF SCALAR UANTITY

1. !calar *uantity can be added, subtracted, multiplied, di%ided according to the ordinary

algebraic rule.2. Two scalars are e*ual if they ha%e same unit.

REPRESENTATION

$t can be represented by the numbers with decimals. (Positi%e negati%e)

E AMPLE

Mass, 3istance, Temperature, %olume, speed e.t.c

ECTOR #DE8T4F *uantities are those physical *uantities which do not re*uire only theirmagnitude e'press with suitable unit. ut they also re*uire a particular direction for completetheir specification is called %ector *uantity.#

4F

Dector *uantity are those physical *uantity which re*uire magnitude, e'press withsuitable unit as well as proper direction is called %ector *uantity.#

CHARACTERISTICS OF ECTOR UANTITY

1. Dector *uantity cannot be added, subtracted, multiplied, and di%ided according to theordinary algebraic rule.

2. $t can be added, subtracted, multiplied, and di%ided according to the some special rulesli-e head and tail rule, 7raphical method e.t.c.

3. Dector always treats as positi%e.

REPRESENTATION

$t can be represented by an arrow with headline. The length of an arrow represents its

magnitude and the headline represents the direction of the %ector(figure ;.;)



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I (figure ;.;)

E AMPLE

@eight, 3isplacement, Delocity, cceleraton, Tor*ue, Momentum e.t.c

ADDITION OF A ECTOR

#The process of combining of two or more %ector to produce a signal %ector ha%ing thecombining effect of all the %ector is called the resultant of the %ector and this process is-nown as the addition of a %ector#.

HEAD AND TAIL RULE

!uppose we ha%e two %ector and ha%ing the different magnitude and direction.

1. Cirst of all chose a suitable scale and representation of all the %ector ha%e been drawnon the paper.

2. Put all the %ector for finding the resultant of gi%en %ector such that the head of the first%ector oin the tail of the second %ector.

3. Jow oin the tail of the first %ector with tail of the second %ector such that it oin thetwo %ector with head to head and tail to tail by another.

4. The new %ector F will be the resultant of the gi%en %ector.

5. $t can be measured by the 3ee or any suitable mean. This method is called the headand tail or tip to tail rule.


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%ector which is not along ' a'is or y a'is it can be resol%ed into infinite number, butgenerally a %ector can be resol%ed into its components at a right angle to each other

MATHEMATICALLY PRO ED suppose a %ector C is denoted by a line which ma-es anangle G with hori&ontal surface 4 . Crom a point draw perpendicular to the hori&ontalsurface 4 .


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MOTION

#@hen a body changes its position with respect to its surrounding so the body is said tobe in the state of motion#.

TYPES OF MOTION

There are three types of motion"

1. Linear or Translatory motion

2. Fotatory motion

3. Dibratory motion

1. LINEAR OR TRANSLATORY MOTION

$f a body mo%es in a straight path so the body is to be in Linear motion or Translatorymotion.

E +$

bus is mo%ing on the road, person is running on the ground.

2. ROTATORY MOTION

$f a body spins or rotates from the fi'ed point ,so the body is to be in Fotatory motion.

E +$ The blades of a mo%ing fan, The wheel of a mo%ing car.

3. IBRATORY MOTION

To and fro motion about the mean point so the body is to be in Dibratory motion.

E +$

Motion of a spring.

REST

#@hen a body does not change its position with respect to its surrounding so the bodyis said to be in the state of rest#.

E +$

boo- is laying on the table, person is standing on floor, tree in the garden.

SPEED

#The distance co%ered by a body in a unit time is called speed.#

4F

#The rate of change of distance is called speed.#



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FORMULA

!peed 3istance


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or Df Di at (;)

!ubstituting the a%erage %elocity"

Da% (Di Df)


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1. @hen a body is thrown %ertically upward, its %elocity continously decreases andbecome &ero at a particular height 3uring this motion the %alue of acceleration isnegati%e and Df is e*ual to &ero (a =.0m$ B, ? * * M,%*,

Jewton:s Law states that when a body is mo%ing, it mo%es in a straight line withuniform %elocity, but when we apply an opposite force, it changes its state of motion andcome to rest.

E +$



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body riding a push bi-e along a le%eled road does not come to rest immediatelywhen we apply a force, it changes its state of rest and starts mo%ing along a straight line.

$f a bus suddenly starts mo%ing, the passengers standing in the bus will fall in thebac-ward direction. $t is due to the reason that the lower part of the passengers which is incontract with the floor of the bus is carried forward by the motion of the bus, but the upperpart of the body remains at rest due to inertia and so the passengers fall in bac-warddirection.

SECOND LA" OF MOTIONS

STATEMENT

#@hen a force acts on an ob ect it produces an acceleration which is directly proportionto the amount of the force and in%ersely proportional to the product of mass#

E PLANATION

$t is well -nown fact that if we push a body with greater force then its %elocityincreases and change of %elocity ta-es place in the direction of the force. $f we apply a certainforce C on a mass m, then it mo%es with certain %elocity in the direction of the force. $f theforce becomes twice then its %elocity will also increase two times. $n this way if we go onincreasing the fore there will be increase in %elocity, which will increase the acceleration.

DERI ATION

ccording to the Jewton s !econd law of motion when a force acts on an ob ect itproduces an acceleration which is directly proportion to the amount of the force.

a U C Nhere U is the sign of directly proportional " 3o not write this sentence ine'amination O

nd in%ersely proportional to the product of mass

a U ;


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Corce is an agent which produces motion in a body but some time force may not besucceeded to produce motion in a body so we can say that the force is an agent whichproduces or tends to produce motion in a body.

"$ 0 8&%>$& ? %> %)

Corce is an agent which stops or tends to stop the motion of a body. $n simple word wecan also say that force is an agent which changes or tends to change the sate of an ob ect.

2. MASS

The *uantity of matter contained in a body is called mass.

FORMULA

C ma

m C


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LA" OF CONSER ATION OF MOMENTUM

The law of conser%ation of momentum is a fundamental law of nature, and it statesthat the total momentum of a isolated system of ob ects (which has no interactions withe'ternal agents) is constant. 4ne of the conse*uences of this is that the centre of mass ofany system of ob ects will always continue with the same %elocity unless acted on by a forceoutside the system

E AMPLE

8onsider two bodies and of mass m; and m6 mo%ing in the same direction with%elocity 5; and 56 respecti%ely such that 5; is greater than 56. !uppose the ball ac*uire%elocity D; and D6 respecti%ely after collision

Momentum of the system before collision m;5; m656

Momentum of the system after collision m;D; m6D6

ccording to the law of conser%ation of momentum"

Total momentum of the system before collision Total momentum of the system after

collision 1U1 2U2 @ 1 1 2 2

FRICTION

D$ * *%*,

#@hen a body mo%es o%er the surface of another body then the opposing force isprodece and this opposing force is called force of friction#

E + %*,

!uppose a wooden bloc- is placed on a table and a spring balance is attached on it. $fwe apply a %ery small force of magnitude C by pulling the spring gradually and increase it, weobser%e that the bloc- does not mo%e until the applied force has reached a critical %alue. $f Cis less then critical %alue, the bloc- does not mo%e. ccording to Jewton:s Third Law ofmotion an opposite force balance the force. This opposing force is -nown as the force offriction or friction.

C 8 $ , F&*0%*,

$f we see the surface of material bodies through microscope, we obser%e that they arenot smooth. E%en the most polished surfaces are une%en. @hen one surface is placed o%eranother, the ele%ations of one get interloc-ed with the depression of the other. Thus theyoppose relati%e motion. The opposition is -nown as friction.

F 0%,& , *0> F&*0%*, D$ $

The force of friction depends upon the following factors"

1. N,& + R$ 0%*, (R!

Corce of friction is directly proportional to normal reaction (F), which act upon the bodyin upward direction against the weight of the body sliding on the surface.

2. N %8&$ , S8& 0$

Corce of friction also depends upon the nature of the two surfaces. $t is denoted as uand has constant %alues for e%ery surface. $t is different for the two surfaces in contact.



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The %alue of limiting friction increases proportionally with the increase in normalreaction. Hence, liming friction C(s) is directly proportional to the normal reaction.

C(s) U F (Here U represents the sign of proportionality dont: write it in the e'aminationpaper.)

I Cs uF........... (i)

u C(s)


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Tor*ue Corce S moment arm

T @ F G

CENTRE OF 'RA ITY

The centre of gra%ity is a point at which the whole weight of the body appears to act.

CENTRE OF 'RA ITY OF RE'ULAR SHAPED OB=ECTS

@e can find the centre of gra%ity of any regular shaped body ha%ing the followingshapes"

;. T&* +$) The point of intersection of all the medians.

6. C*&0+$) 8entre of gra%ity of circle is also the centre of gra%ity.

B. S 8 &$) Point of intersection of the diagnonals.

?. P & ++$+, & ) Point of intersection of the diagonals.

1. S >$&$) 8entre of the sphere.

CENTRE OF 'RA ITY OF IRRE'ULAR SHAPED OB=ECTS

@e can find the center of gra%ity of any irregular shaped ob ect by using followingmethod. 3rill a few small holes near the edge of the irregular plate. 5sing the hole , suspendthe plate from a nail fi'ed hori&ontally in a wall. The plate will come to rest after a fewmoments. $t will be in a position so that its centre of gra%ity is %ertically below the point ofsuspension.

Jow, suspend a plumb line from the supporting nail. 3raw a line : in the plate alongthe plumb line. The centre of gra%ity is located somewhere on this line.

Fepeat the same process using the second hole . This gi%es the line : on the plate.lso repeat this process and use hole 8 and get line 88:.

The lines :, : and 88: intersect each other at a point. $t is our re*uired point, i.e.ethe centre of gra%ity. @e can use this procedure with any irregular shaped body and find outits centre of gra%ity.

E UILIBRIUM

body will be in e*uilibrium if the forces acting on it must be cancel the effect of eachother.

$n the other word we can also write that"

body is said to be in e*uilibrium condition if there is no unbalance or net force actingon it.

STATIC E UILIBRIUM

@hen a body is at rest and all forces applied on the body cancel each other then it issaid to be in static e*uilibrium.

DYNAMIC E UILIBRIUM

@hen a body is mo%ing with uniform %elocity and forces applied on the body canceleach other then it is said to be in the dynamic e*uilibrium.

CONDITIONS OF E UILIBRIUM

FIRST CONDITION OF E UILIBRIUM



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# body will be in first condition of e*uilibrium if sum of all forces along a'is and sumof all forces along Y a'is are are e*ual to &ero, then the body is said to be in first condition ofe*uilibrium.#

( F @ F? @ !

SECOND CONDITIONS OF E UILIBRIUM

# body will be in second condition of e*uilibrium if sum of cloc-wise(Moment) tor*ue

must be e*ual to the sum of anticloc-wise tor*ue(Moment), then the body is said to be insecond condition of e*uilibrium.#

S8 , %,& 8$ @

STATES OF E UILIBRIUM

There are following three states of E*uilibrium"

1. FIRST STATE (STABLE E UILIBRIUM!

body at rest is in stable e*uilibrium if on being displaced, it has the tendency tocome bac- to its initial position.

@hen the centre of gra%ity of a body i.e. below the point of suspension or support,then body is said to be in stable e*uilibrium.

2. SECOND STATE (UNSTABLE E UILIBRIUM!

$f a body on displacement topples o%er and occupies a new position then it is said to bein the state of unstable e*uilibrium.

@hen the centre of gra%ity lies abo%e the point of suspension or support, the body issaid to be in the state of unstable e*uilibrium.

3. THIRD STATE

$f a body is placed in such state that if it is displaced then neither it topples o%er nordoes it come bac- to its original position, then such state is called neutral e*uilibrium.

@hen the centre of gra%ity of a body lies at the point of suspension, then the body issaid to be in neutral e*uilibrium.

CHAPTER NO. 7 CIRCULAR AND 'RA ITATION

CENTRIPETAL FORCE

DEFINITION

#The force that causes an ob ect to mo%e along a cur%e (or a cur%ed path) is calledcentripetal force.#

M %>$ %*0 + E &$ *,

@e -now that the magnitude of centripetal acceleration of a body in a uniform circularmotions is directly proportional to the s*uare of %elocity and in%ersely proportional to theradius of the path Therefore,

a(c) U %6 (Here U represents the sign of proportionality do not write this in your e'aminationand 6 represents s*uare of %)

a(c) U ;


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Crom Jewton:s !econd Law of Motion"

C ma

I F(0! @ 2;&

@here,

Cc 8entripetal Corce

m Mass of ob ect

% Delocity of ob ect

r Fadius of the cur%ed path

F 0%,& , *0> F0 D$ $ )

Cc depends upon the following factors"

$ncrease in the mass increases Cc.

$t increases with the s*uare of %elocity.

$t decreases with the increase in radius of the cur%ed path.

E +$

The centripetal force re*uired by natural planets to mo%e constantly round a circle ispro%ided by the gra%itational force of the sun.

$f a stone tied to a string is whirled in a circle, the re*uired centripetal force is suppliedto it by our hand. s a reaction the stone e'erts an e*ual force which is felt by our hand.

The pilot while turning his aeroplane tilts one wing in the upward direction so that theair pressure may pro%ide the re*uired suitable Cc.

CENTRIFU'AL FORCE

D$ * *%*,

# force supposed to act radially outward on a body mo%ing in a cur%e is -nown ascentrifugal force.#

E + %*,

8entrifugal force is actually a reaction to the centripetal force. $t is a well -nown factthat Cc is directed towards the centre of the circle, so the centrifugal force, which is a force ofreaction, is directed away from the centre of the circle or the cur%ed path.

ccording to Jewton:s third law of motion action and reaction do not act on the same

body, so the centrifugal force does not act on the body mo%ing round a circle, but it acts onthe body that pro%ides Cc.



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E +$

$f a stone is tied to one end of a string and it is mo%ed round a circle, then the forcee'erted on the string on outward direction is called centrifugal force.

The aeroplane mo%ing in a circle e'erts force in a direction opposite to the pressure ofair.

@hen a train rounds a cur%e, the centrifugal force is also e'erted on the trac-.

LA" OF 'RA ITATION

I %&, 80%*,

Jewton proposed the theory that all ob ects in the uni%erse attract each other with aforce -nown as gra%itation. the gra%itational attraction e'ists between all bodies. Hence, twostones are not only attracted towards the earth, but also towards each other.

S% %$ $ %

E%ery body in the uni%erse attracts e%ery other body with a force, which is directlyproportional to the product of masses and in%ersely proportional to the s*uare of the distancebetween their centres.

M %>$ %*0 + E &$ *,

Two ob ects ha%ing mass m; and m6 are placed at a distance r. ccording to Jewton:sLaw of 5ni%ersal 7ra%itation.

C U m;m6 ((Here U represents the sign of proportionality do not write this in youre'amination)

lso C U ;


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5. "ATT

@att is the unit of power that is e*ual to the *uantity of ; 9oule wor- done in ; second.

"ORK

@hen a force produces displacement in a body, it is said to do wor-.

UNITS OF "ORK

!.$ !ystem 9oule

8.7.! !ystem Erg

E + %*,

@hen force is applied in the direction of the displacement we can find the wor- byusing definition

@or- Corce S 3isplacement

@ CSs

" @ F

!uppose a man is pulling the grass cutting machine then the direction of the foce anddisplacement is not same. The applied force ma-es an angle G with the ground while themotion ta-es place along the ground.

$n this case force is resol%ed into its components.

C' CcosG

Cy CsinGs the machine mo%es along the ground, so C' is doing the wor-, Hence"

@ Corce S 3isplacement

@ CcosGSs

"@F 0,

ENER'Y

Energy is define as the capability to do wor-. Energy is also measured in 9oules.

S, $ T? $ , E $& ?

Potential Energy/inetic Energy8hemical EnergyHeat EnergyLight EnergyJuclear Energy

POTENTIAL ENER'Y

D$ * *%*,

The energy possessed by a body due to its position is -nown as the Potential Energy ofthe body. $t is represented by P.E. and is measured in 9oules in !ystem $nternational.



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E +$

The energy of the following is potential energy"

bric- lying on the roof of a house.The spring of a watch when wound up.The compressed spring.@ater stored up in ele%ated reser%oir in water supply system.

M %>$ %*0 + E &$ *, $f we lift a body of mass m to a height h, then the force applied on it is the its weight

and it will act through a distance h.

!o,

@or- Corce S 3istance

@ @ S h

!ince @ mg, therefore"

@ mg S h

!ince wor- is e*ual to energy possessed by a body"

P.E. @ >

KINETIC ENER'Y

D$ * *%*,

The energy possessed by a body due to its motion is -nown as the /inetic Energy ofthe body. $t is represented by /.E.

E +$

The energy of the following is -inetic energy"

bullet fired from a gun. railway engine mo%ing at high speed.Motion of a simple pendulum.

M %>$ %*0 + E &$ *,

8onsider a body of mass at rest ( * @ ! on a frictionless surface. @hen a force C isapplied, the body co%ers a distance S and its final %elocity becomes .

To calculate the amount of wor- done, we apply the formula.@ C S !

ccording to Jewton:s !econd Law of Motion, the %alue of force is"

C ma

The distance that the body tra%eled is calculated by using third e*uation of motion"

6as %f6 %i6 (Here 6 with Df and Di represents s*uare)

@e -now that Di 2, therefore"

6as %6

s %6


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y substituting the %alues of C and s, we get"

@ (ma) S (%6


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E(A! @ >

!uppose the body is released from this height and falls through a distance . $ts newheight will be (>- ! . The %elocity with which it reaches point B is calculated by using the thirde*uation of motion"

6gs Df6 Di6

s we -now"

Di 2! '

Therefore,

6g' Df6 2

6g' %6

The -inetic energy at point is"

/.E. ;$ %*0 + E &$ *,

Power Fate of doing @or-

Power @or-


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NEED TO CONSER E ENER'Y

The fuel that burns in running factories, transport and other acti%ities is mainlyobtained from underground deposits in the form of coal, oil, gas and other similar raw forms.These deposits are rapidly decreasing and one day all these resources of energy will beconsumed. $t is therefore highly important for us to a%oid wastage of energy.

The consumption of two much energy is also ha%ing ad%erse effect on ouren%ironment. The air in big cities is hea%y because of pollution caused by industrial wastesand smo-e produced by automobiles. To ensure comfortable li%ing with a neat en%ironment,it is the responsibility of all of us as indi%iduals to conser%e energy.

CHAPTER NO. 9 MACHINES

3EC$J$T$4J!

1. MACHINE

machine is a de%ice by means of which useful wor- can be performed con%enientlyand it can also transfer one form of energy into another form of energy.

2. MECHANICAL AD ANTA'E

The ratio between the resistance or weight to the power applied in a machine is calledthe mechanical ad%antage of that machine. $t is denoted by M. .

M.A. @ "$* >% , $&-0, $ ? M 0>* $; F,&0$ A +*$ , %>$ M 0>* $

3. EFFICIENCY

The ratio between the useful wor- done and the wor- done on the machine is calledefficiency.

M.A @ (,8% 8%;I 8%! G 1

4. INPUT

$nput is the wor- done on the machine.

5. OUTPUT

4utput is useful wor- done by the machine.

LE ER

D$ * *%*,

Le%er is the simplest machine in the world. $t is a rigid bar, which can be rotated abouta fi'ed point.

P&* 0* +$ , L$ $&

$n the le%er the moment P acts opposite to that of wor- @. $t means that force C tendsto rotate the le%er in one direction which the wight @ rotates in opposite direction. $f themagnitude of these moments acting in opposite direction is e*ual, then the le%er will be ine*uilibrium. $t means that"

Moment of P Moment of @

M$0> *0 + A % $



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@e -now that according to Principle of Le%er"

Moment of P Moment of @

I Corce S Corce rm @eight S @eight rm

P S @ 8

< 8 @% A& ; F,&0$ A&

KINDS OF LE ER

1. FIRST KIND OF LE ER

$n the first -ind of le%er, the fulcrum C is in the between the effort P and @eight @.

E +$

Physical alanceHandle of PumpPair of !cissors!ee !aw

2. SECOND KIND OF LE ER

$n the second -ind of le%er, the weight @ is in between the fulcrum C and effort P.

E +$ 3oorJut 8rac-erPunching Machine

3. THIRD KIND OF LE ER

$n the third -ind of le%er, the effortP is in between the fulcrum C and weight @.

E +$

Human forearm5pper and Lower 9aws in the Mouth. Pair of Corecepes

INCLINED PLANE

D$ * *%*,

hea%y load can be lifted more easily by pulling it along a slope rather than by liftingin %ertically. !uch a slope is called an $nclined Plane.

M$0> *0 + A % $

M.A @ ";P @ +;> @ L$ %> , I 0+* $ P+ $;P$& $ *08+ & H$* >%



29/78

PULLEY

pulley consists of a wheel mounted on an a'le that is fi'ed to the framewor- calledthe bloc-. The wheel can rotate freely in the bloc-. The groo%e in the circumference pre%entsthe string from slipping.

FI ED PULLEY

$f the bloc- of the pulley is fi'ed then it is called a fi'ed pulley.

M$0> *0 + A % $ , F* $ P8++$?

$n a fi'ed pulley, the force P is the applied force and weight @ is lifted. $f we neclectthe force of friction then"

Load Effort

$n the gi%en case"

Load @ S Load rm

Load @ S 4lso,

Effort P S Effort rm

Effort P S 4

!o,

@S4 PS4

I @


30/78

Hence, the mechanical ad%antage of a mo%eable pulley is 6.

CHAPTER NO. 1 MATTER

DEFINITION OF MATTER

# nything ha%ing mass and %olume is called matter.#KINETIC MOLECULAR THEORY OF MATTER

The /inetic Molecular Theory of Matter has the following postulates"

Matter is made up of %ery small particles called molecules.

These molecules are in the same state of motion, hence they possess -inetic energy.Their motion can be translatory, %ibratory or rotational.

The molecules attract each other with a force. This force depends upon the distancebetween them. Corce is in%ersely proportional to the distance between the molecules.

@hen a substance is heated its temperature as well as molecular motion increases.3ue to this motion, -inetic energy also increases. we can say that when the -inetic energy ofthe molecules increases, then temperature of the substance rises.

BRO"NIAN MOTION

$n ;06>, a scientist, Fobert rown obser%ed the motion of molecules with the help of amicroscope. He obser%ed that the tiny particles in water are constantly mo%ing in a &ig&agpath. He called the motion, rownian Motion.

E + %*,

The cause of this tiny particle motion is the rapid motion of the molecules, whichcollide with the particles and push them in one direction. $f some molecules come from otherdirection and collide with the same particles, particles change their direction. This processcontinues and the motion becomes &ig&ag.

STATES OF MATTER Matter has been classified into three states. These states are discussed below"

1. SOLID

ccording to the -inetic theory of matter, solid has the least -inetic energy. Theproperties of solids are gi%en below"

The particles are %ery close to each other.Their shape and %olume is fi'ed.Particles in a solid %ibrate to and fro from their mean position.4n heating they melt and con%ert into li*uid.!ome solids also con%ert directly into gas on heating.



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2. LI UID

ccording to the -inetic theory of matter, li*uids ha%e the following propertiesThey ha%e greater -inetic energy than solids but less than that of gases.The %olume of li*uid is fi'ed.They mo%e more freely than solids.The attraction between molecules is lower than solids.The distance between the molecules is greater than that of solids.

4n heating, they con%ert into %apours.4n cooling, they con%ert into solid.

3. 'AS

ccording to the -inetic molecular theory, gases possess the following properties.7ases possess more -inetic energy.Their shape and %olume are not fi'ed.The distance between their molecules is large.Their temperature is proportional to their -inetic energy.Their temperature rises with increase in pressure.4n cooling, they con%ert into li*uid and gases.

ELASTICITY

D$ * *%*,

The tendency of a material to return to its original dimension after the deformingstress has been remo%ed is -nown as elasticity.#

$f we apply a force to a body, it is stretched. @hen the applied force is remo%e, thebody returns to its original shape. The phenomenon of turning bac- to its original shape iscalled Elasticity.

ELASTIC BEHA IOUR AND MOLECULAR THEORY

The elastic beha%iour of a material can be e'plained by the /inetic Theory of Matter.!ince the molecules in a solid are %ery close to each other, there e'ist strong attractingforces between them. Thus when force is remo%ed, the attraction forces between themolecules pull them bac- again and the material is restored to its original shape. 3ifferentmaterial ha%e different elasticity depending on the nature of the material.

E+ %*0 L* *%

The ma'imum resisting force of a material is called the Elastic Limit of that material.

STRESS

D$ * *%*,

#@hen a body is made to change its length, %olume or shape by the application of ane'ternal force, the opposing force per unit area is called !tress.#

F,& 8+



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!tress Corce < rea

, @ F;A (Here o represents (Fho) do not write in your e'amination paper)

U *%

!.$ or M/! !ystem J


33/78

E+ %*0 R$ *,

@hen the material obey:s Hoo-:s Law, it is said to be in Elastic Fegion.

P+ %*0 R$ *,

@hen stress is applied beyond the elastic limit, the graph is no longer a straight line. $nthis case stress produces a permanent change in the material. The material is said to be in itsPlastic Fegion.

B&$ /* P,* %

The material brea-s at a certain point called the rea-ing Point of the material.

YOUN'JS MODULUS

D$ * *%*,

#The ratio of the stress on a on a body to the longitudinal strain produced is calledYoung:s Modulus.#

M %>$ %*0 + E &$ *,

ccording to the definition of Y4ung:s Modulus"

Young:s Modulus !ress < Longitudinal !train

U *%

$n !.$ system, Young:s Modulus is measured in J$ %*0 + E &$ *,

Pressure Corce < rea

P @ F;A

U *% !.$ or M./.! !ystem J


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S% %$ $ %

@hen a pressure is applied to a li*uid contained in a %essel, it is transmittedundiminished e*ually in all directions and acts perpendicularly to the walls of the container.

A +*0 %*, - H? & 8+*0 P&$

Pascal:s Principle has the application in Hydraulic press. $n a hydraulic press a narrowcylinder is connected with a wider cylinder and they are fitted with airtight piston. $t isfilled with some incompressible li*uid. Pressure can be applied by mo%ing the piston cylinder in the downward direction. Piston is used to lift the ob ect. The hydraulic press is pro%idedwith a rigid roof o%er it. @hen piston mo%es upward, it compresses any material placedbetween the rigid roof and this piston. The hydraulic press is used for compressing softmaterials li-e cotton into a cotton bale and powdered materials into compact solids.

(3iagram)

PRESSURE IN 'ASES

The -inetic theory enables us to account for the pressure a gas e'erts on the walls ofits container. @hen a mo%ing molecule stri-es the walls of its container, a force is e'erted on

the walls during hte impact.

ATMOSPHERIC PRESSURE

The atmosphere, because of its weight e'erts a pressure on the surface of the earthand on e%ery ob ect on the earth including human beings. The pressure is -nown astmospheric Pressure.

A +*0 %*, , A% , >$&*0 P&$ 8&$

The fact that the atmosphere e'erts pressure has been put into use in se%eral de%icessuch as siphons, pumps and syringes.

BAROMETER

D$ * *%*,

# de%ice for measuring the atmospheric pressure is called arometer.#

M$&08&? B &, $%$&

$n the laboratory, the atmospheric pressure is measured by means of a mercurybarometer. mercury barometer consists of a thic- walled glass tube of ;m length, which isopened at one end and closed from the other side. The tube is filled with mercury. The open

end is firmly co%ered with a thumb and then carefully in%erted in a %essel containingmercury. @hen the open end is completely immersed in the mercury, the thumb is remo%ed.!ome of the mercury from the columns drops in the %essel lea%ing a space. This space iscalled %acuum. $f the mercury columns is measured, it is found to be >A2 mm. This lengthalways remains constant e%en if different diameter tubes are ta-en. The length of themercury column is referred to as the atmospheric pressure.

ARCHIMEDEJS PRINCIPLE

S% %$ $ %

#@hen an ob ect is immersed in a li*uid, an upward thrust acts upon it, which is e*ualto the weight of the li*uid displaced by the ob ect.#



35/78


36/78

Temperature is the degree of hotness or coldness of a body.$t is the a%erage -inetic energy of the body.Temperature is measured using thermometer.$ts units are C, 8 and /.

THERMAL E PANSION

8hange in length, breadth and height of a body due to heating is -nown as ThermalE'pansion. $t occurs in all the three states, i.e. solids, li*uids and gases.

THERMAL E PANSION OF SOLIDS

!olids e'pand on heating. Their ability to e'pand depends on their molecular structure.s the temperature is increased, the a%erage -inetic energy of the molecules increases andthey %ibrate with larger amplitudes. This results in increase in the distance between them.Hence, they e'pand on heating. Thermal E'pansion of solids can be classified into threetypes.

1. LINEAR THERMAL E PANSION

8hange in length or any one dimension of a solid on heating is -nown as L$nearThermal E'pansion.

2. REAL E PANSION

The sum of the obser%ed increase in the %olume of a li*uid and that of the containing%essel is called real Thermal e'pansion.

Feal E'pansion pparent E'pansion E'pansion of the Dessel

3. APPARENT E PANSION

pparent E'pansion is the e'pansion in which only the e'pansion of li*uid is consideredand e'pansion of the %essel is not ta-en into account. pparent e'pansion is less the reale'pansion.

ANOMALOUS E PANSION OF "ATER

The increase in the %olume of water as its temperature is lowered from ? 8 to 28 is-nown as anomalous e'pansion of water.

E $0% , A , +,8 E *, , " %$&

1. $n winter, the temperature in the north and south poles of the earth falls. s thetemperature fall below ? 8 water on the surface e'pands and stays afloat. $cecontinues building up at the surface while the temperature at the bottomremains at ? 8. This helps fish and other forms of marine life to li%e.

2. 3uring the rainy season a lot of water seeps through the crac-s in the roc-s. $nwinter, when the water e'pands, the roc- get bro-en due to this e'pansion.

3. $n cold climate, water supply pipes burst when the water e'pands on cooling.

'AS LA"S

1. BOYLEJS LA"



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The %olume of a gi%en mass of a gas is in%ersely proportional to the pressure, $f thetemperature is -ept constant.

P U ;


38/78

2. CLINICAL THERMOMETER

I %&, 80%*,

clinical thermometer is a de%ice that is used to find the temperature of the humanbody. $t has a range from B1 8 to ?B 8 (=1C to ;;2C).

C, %&80%*, $t consists of a glass stem with a capillary tube, ha%ing a small bulb at one end. This

bulb is filled with a li*uid usually mercury or alcohol colored with a red dye. The upper end ofthe capillary tube is sealed so that the li*uid will neither spill nor e%aporate. The air from thecapillary tube is also remo%ed. The glass stem of a clinical thermometer has a construction inits capillary tube near the bulb. This helps to stop the mercury thread from mo%ing bac-when the thermometer is remo%ed from the patient:s mouth.

",&/*

$n order to find out the temperature, the thermometer is placed in the mouth or in thearm pit of the patient. The li*uid in it e'pands and rises in the tube. temperature scale ismr-ed on the glass stem to indicate temperatures according to the %arious le%els of li*uid inthe tube.

3. MA IMUM AND MINIMUM THERMOMETER

I %&, 80%*,

This thermometer is used to read the ma'imum and minimum temperatures reachedo%er a period of time.

C, %&80%*, This thermometer consists of a fairly large cylindrical bulb with alcohol in it. This bulb is

connected through a 5 shaped tube filled mercury. t the end of this 5 shaped tube anotherbulb containing alcohol is pro%ided.

",&/*

@hen the bulb is heated, alcohol in it e'pands and dri%es the mercury round towardsthe other end of the 5 shaped tube. This mercury e'erts pressure on the alcohol in thesecond bulb and its le%el rises. 4n each mercury surface, there is a small iron inde' pro%ideswith a light spring to hold it in position in the tube. @hen the mercury thread is mo%ed, dueto e'pansion or contraction of alcohol in the first bulb, the indices mo%es and are left in thee'treme positions reached o%er a period of time. The lower end of the inde' on the leftindicates the minimum and that on the right indicates the ma'imum temperature.

HEAT TRANSFER

There are three methods of transferring heat from one place into another.

1. CONDUCTION

8onduction is a mode of heat transfer by atomic or molecular collisions, without themo%ement of a bul- of a substance from one position to another, in a body. $t mostly occursin solids.



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2. CON ECTION

8on%ection is a mode of heat transfer by the actual mo%ement of the bul- of thesubstance from one place to another through large distances. $t mostly occurs in li*uids andgases.

3. RADIATION

Fadiation is a mode of heat transfer which re*uires no material medium. Heat energyis carried by infra red electromagnetic wa%es from one place to another.

BI-METALLIC STRIPS

bi metallic strip is made of pieces of two different metals of different e'pansionrates, e.g. iron and brass. @hen it is heated, it bends with the brass on the outside of thecur%e because brass e'pands more *uic-ly than iron.

1. BI-METAL THERMOMETER

I %&, 80%*,

bi metal thermometer is made of a bi metallic coil. Jo li*uid is used in such type ofthermometer.

C, %&80%*,

$t consists of a bi metallic strip in the form of a long spiral. 4ne end of the spiral is-ept fi'ed, while a light pointer is attached to the other end.

",&/*

@hen the temperature rises, the bi metal strip coil itself into an e%en tighter spiral dueto different e'pansion rates of the two metals. the pointer mo%es across the temperaturescale and in this way reading is noted.

2. FIRE ALARM

I %&, 80%*,

fire alarm is used to warn people when there is a fire.

C, %&80%*,

$n a fire alarm, one end of a bi metal strip is firmly fi'ed, while the other is free. 4neterminal of a A %olt battery is connected to the fi'ed end of the strip through a A %olt bulb orbell. The other terminal of the battery is connected with a metallic contact which is ust abo%ethe free end of the bi metallic strip.



40/78

",&/*

@hen a fire starts, heat energy is gi%en off. $t raises the temperature of the bi metallicstrip and its free end bends towards the contact. 4n touching the contact, electric circuit getscompleted and the bulb starts to glow or in case of a bell, it rings warning about the fire.

LATENT HEAT OF FUSION

The *uantity of heat re*uired to transform ; -g of ice completely melts into water at28 is -nown as Latent Heat of Cusion.

LATENT HEAT OF APORI#ATION

The *uantity of heat re*uired to transform ; -g of water completely into steam at ;228 is -nown as Latent Heat of Dapori&ation.

EFFECT OF PRESSURE ON MELTIN' POINT (RE'ELATION! The melting point of those substances, which e'pand on free&ing, gets lowered whenpressure oe%er one atmosphere is e'erted on them.

E $&* $ %

Ta-e a bare copper wire with weights on its both ends. Place it across a bloc- of ice.The copper wire sin-s slowly through the bloc- and weight falls to the floor. Pressure e'ertedby the copper wire lowers the free&ing point of ice and the ice beneath the wire melts. Thewater flows round the wire and re free&es on getting abo%e the wire, releasing latent heatenergy. This energy is conducted through the copper wire, which helps to melt the ice belowthe wire. $n this way, ice below the wire melts while water abo%e the wire free&es. Thisprocess continues until the wire cuts through the ice bloc-.

EFFECT OF PRESSURE ON BOILIN' POINT

$f the pressure on the surface of a li*uid is increased abo%e the normal atmosphericpressure, its boiling point increases.

E $&* $ %

Cill a round bottom flas- to half its capacity. fter boiling the water fro a few minutes,remo%e the burner and place a cor- in the flas-. $n%ert the flas- and pour some cold water onthe bottom of the flas-. fter some time, water starts to boil again although no more heathas been pro%ided to it. The reason is that, when the water was boiled, it e'pelled all the airfrom the flas-. @hen the flas- was cor-ed and allowed to cool the steam condensed intowater. !ince, no fresh air could enter the flas- the pressure inside the flas- lowered. Thisdecreased the boiling point of water and water started to boil at normal temperature.

E APORATION



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The process of change of a li*uid into %apour without boiling is called e%aporation.

FACTORS ON "HICH E APORATION DEPENDS

E%aporation depends on the following factors"

1. N %8&$ , L* 8* ) $f the boiling point of a li*uid is low, then they e%aporatemuch *uic-ly e.g. lcohol and Ether.

2. T$ $& %8&$ , L* 8* ) $f the surface temperature of a li*uid is increased,then rate of e%aporation also increases, e.g. ironing of clothes.

3. S8& 0$ A&$ , L* 8* ) $f the surface area of a li*uid is increased, then therate of e%aporation increases, e.g. li*uids spread o%er large areas e%aporatemore *uic-ly.

4. D&? $ , A*&) $f there is more dryness in the air, then the rate of e%aporationincreases, e.g. in humid weather, clothes ta-e a longer time to dry.

5. "* $$ ) $f the wind speed is greater, then e%aporation rate increases.

6. A*& P&$ 8&$ , %>$ S8& 0$ , T>$ L* 8* ) $f the pressure on the surface ofthe li*uid is increased, the rate of e%aporation decreases.

LA" OF HEAT E CHAN'E

Cor an isolated system comprising mi'ture of hot and cold substances, the heat lost byhot substances is e*ual to the heat gained by cold substances.

H$ % +, % ? >,% , ? @ H$ % * $ ? 0,+ , ?

REFRI'ERATOR

I %&, 80%*,

refrigerator is a de%ice that is used to -eep fruits, %egetables and other eatablescool.

C, %&80%*,

refrigerator consists of a compressor, condenser and e%aporator.

REFRI'ERANT

Creon is used as the refrigerant in a referigerator. This gas li*uifies at normaltemperature if the pressure is increased.

",&/*

1. C, &$ *, ) Creon gas is first compressed in the compressor of a refrigerator.$t is then fed into the condenser.

2. C, $ %*, ) $n the condenser, the gas is li*uified under pressure. $t con%ertsinto a li*uid at normal temperature. This gas is then allowed to pass through a%al%e into the e%aporator.

3. E ,& %*, ) The pressure in the e%aporator is comparati%ely less than in thecondenser. Therefore, when li*uid Creon enters the e%aporator, it e%aporates



42/78

absorbing a large amount of heat. This results in cooling the area around thee%aporator. This is where we -eep our eatables.

(D* & !

The gas is then again fed into the compressor and the process continues.

CHAPTER NO. 12 "A E AND SOUND

DEFINITIONS

1. IBRATION

4ne complete round trip of a simple harmonic motion is called %ibration.

4r

$f a body in periodic motion mo%es to and fro o%er the same path, this motion is called4scillation.

2. TIME PERIOD (T!

The time re*uired to complete %ibration is -nown as time period.3. FRE UENCY

$t is the number of %ibrations e'ecuted by an oscillating body in one second.

4. DISPLACEMENT

$t is the distance of a %ibrating body at any instant from the e*uilibrium position.

5. AMPLITUDE

The ma'imum distance of the body on either side of its e*uilibrium position is -nownas amplitude.

6. "A E LEN'TH

The distance between two consecuti%e crests and troughs is called wa%elength.

7. NATURAL FRE UENCY

The fre*uency at which an ob ect will %ibrate freely (without any e'ternal periodic forceor resistance) is -nown as natural fre*uency of that ob ect.

. AUDIBLE SOUND

4ur ear can hear only those sounds whose fre*uency is between 62H& and 62222H&.This range is -nown as audible sound.

9. ULTRASONIC SOUND

!ound with fre*uency greater than 62222 H& is -nown as ultrasonic sound.

1 . OCTA E

The inter%al between a wa%eform and another of twice the fre*uency is -nown as4cta%e.

UNITS



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F&$ 8$ 0?) 8ycles per second (eps) or Hert& (h&)

" $+$ %>) Meter

I %$ *%? , S,8 ) @att


44/78

Each bridge has its own natural fre*uency and marching of soldiers is another%ibrating system. !o there may occur a force on %ibration in bridge. This may damage thebridge. !o, for safely precautions, it is written that soldiers must march out of stop whilecrossing the bridge.

"A E

D$ * *%*,

# method of energy transfer in%ol%ing some form of %ibration is -nown as a wa%e.#

" $ M,%*,

@a%e motion is a form of disturbance, which tra%els through a medium due to periodicmotion of particles of the medium about their mean position.

E $&* $ %

@e see that if we dip a pencil into a tap of water and ta-e it out a pronounced circularripple is set up on the water surface and tra%els towards the edges of the tub. Howe%er if wedip the pencil and ta-e it out many times, a number of ripples will be formed one after theother.

@a%es can also be produced on %ery long ropes. $f one end of the rope is fi'ed and theother end is gi%en sudden up and down er-, a pulse shaped wa%e is formed which tra%elsalong the rope.

TRANS ERSE "A E

D$ * *%*,

#The wa%e in which amplitude is perpendicular to the direction of wa%e motion is-nown as trans%erse wa%e.#

E +$

Fadio @a%esLight @a%esMicro @a%es@a%es in @ater@a%es in !tring

LON'ITUDINAL "A E

D$ * *%*,

#The wa%e in which amplitude is parallel to wa%e motion is called longitudinal wa%e.#

E +$

!ound @a%es!eismic @a%es

SOUND

D$ * *%*,

# %ibration transmitted by air or other medium in the form of alternate compressionsand rarefactions of the medium is -nown as !ound.#



45/78

P&, 80%*, , S,8

!ound is produced by a %ibrating body li-e a drum, bell, etc, when a body %ibrates. dueto the to and fro motion of the drum, compressions and rarefactions are produced andtransmitted or propagated in air.

P&, %*, , S,8 " $

@hen a body %ibrates in air, it produces longitudinal wa%es by compressions andrarefactions. These compressions and rarefactions are tra%eled by the particles of the mediumand transferred into the ne't particles. 3ue to this transference, sound propagates in amedium.

E $&* $ %

(3iagram)

!uspend an electric bell in a ar by its wires through a cor- fi'ed in its mouth. !witchon the bell, we will hear the sound of the bell. Jow start remo%ing air from ar with the help

of an e'haust (%acuum) pump. The sound will decrease, although the hammer is still seenstri-ing the bell. This e'periment shows that air or any other medium is necessary for thepropagation of sound.

ELOCITY OF SOUND

$t is a matter of common e'perience that the flash of lightning is seen earlier thanhearing the thunder of cloud. !imilarly when a gun is fired its sound is heard a little afterseeing its flash. The reason is that light is faster than sound. 3ue to its slow %elocity soundlags behind.

E $&* $ %

!elect two stations at a distance of 0 -m (or any more distance) such that there is noobstacle between them. Cire a gun at station and note the time of sound ta-en for suchdistance. Fepeat the process and note the time ta-en by the sound to tra%el from to . $fwe substitute the mean of the two times recorded and distance ! (0-m) in the formula D !


46/78

1. LOUDNESS

D$ * *%*,

#Loudness is the magnitude of auditory sensation produce by sound.#

$ntensity can be defined as the energy carried by the sound wa%es through a unit areaplaced perpendicular to the direction of wa%er per second.

F 0%,& E $0%* L,8 $ , S,8

Loudness depend on following factors"

A&$ , * & %*, , B, ?) 7reater will be the surface area more will be theloudness.

A +*%8 $ , M,%*, , * & %* O $0%) 7reater will be the amplitude, more willbe the loudness.

D$ *%? , M$ *8 ) Loudness is directly proportional to the density of medium.

M,%*, D*&$0%*, ) $f source of sound is mo%ing towards the listener loudness willbe greater or if wind supports the %elocity of sound the loudness will be greater.

2. PITCH

D$ * *%*,

#The sensation that a sound produces in a listener as a result of its fre*uency is -nownas Pitch.#

This is the property of sound by %irtue of which we can distinguish between a shrill andgra%e sound.

F 0%,& E $0%* P*%0> , S,8

Pitch depends on following factors"

F&$ 8$ 0? , * & %* B, ?) The greater the fundamental fre*uency, more shrillwill be the sound.

R$+ %* $ M,%*, , S,8 ) $f source and listener both are coming closer pitch willincrease.

3. UALITY OR TIMBRE OR TONE

D$ * *%*,

#The characteristic of a musical note that is determined by the fre*uency present is-nown as uality or Timbre or Tone of that sound.#

This is the property of sound by %irtue of which it is possible to identify a sound of thesame loudness and pitch but originating from different instrument.



47/78

F 0%,& E $0%* 8 +*%?

uality depends upon the following factors"

Phase of the !ound @a%e.!hape of @a%es

HARMFUL EFFECTS OF SOUND (NOISE!

Jowadays noise is considered as a great pollution, which is %ery dangerous for us.!ome of them are as follows"

8ontinuous noise damages hearing and can result in complete deafness.Joise has become a great cause for depression and blood pressure.Mental system shows less efficiency due to noise.8onse*uently it is harmful in all respects for li%ing body.

MUSICAL SOUND

The sound producing pleasing effect on our ears are called musical sounds.

DIFFERENCE BET"EEN LON'ITUDINAL AND TRANS ERSE "A ES

L, *%8 * + " $

1. $n longitudinal wa%es, particles of the medium %ibrate in the direction of the wa%es.

2. The portion of wa%e in which particles of medium are %ery close to each other is calledcompression.

3. E'amples of longitudinal wa%es are sound wa%e and seismic wa%es.

4. 3istance between the centre of two compressions and rarefactions is calledwa%elength.

T& $& $ " $

1. $n trans%erse wa%es, particles of the medium %ibrate in the direction perpendicular tothe direction of wa%e.

2. The portion in which particles of medium are higher than their normal position is calledcrest.

3. E'amples of trans%erse wa%e are microwa%es and radio wa%es.

4. 3istance between two crests and troughs is called wa%elength.

CHAPTER 13 PROPA'ATION AND REFLECTION OF LI'HT

DEFINITIONS

1. INCIDENT RAY

The ray that stri-es the surface of the medium is -nown as $ncident Fay.

2. REFLECTED RAY

The ray that is sent bac- into the same medium after reflection is -nown as reflected ray.



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3. PLANE MIRROR

flat smooth reflecting surface, which shows regular reflection is -nown as plane mirror.

4. NORMAL

Perpendicular line on the reflecting surface is -nown as normal.

5. POLE

The centre of the spherical mirror is called pole.6. AN'LE OF INCIDENCE

The angle subtended by the incident ray to the normal is -nown as angle of incidence.

7. AN'LE OF REFLECTION

The angle subtended by the reflected ray to the normal is -nown as angle of reflection.

. CENTER OF REFLECTION

The center of the hollow sphere of which the mirror is a part is called center of cur%ature.

9. PRINCIPLE A IS

The straight line passing through center of cur%ature nad the pole is -nown as principle a'is.

1 . PRINCIPLE FOCUS

The ray coming parallel to principal a'is after con%erges to or di%erges from a point, which iscalled principle focus.

11. FOCAL LEN'TH

The distance between the principle focus and pole of the mirror is called Cocal Length.

12. RADIUS OF CUR ATUREThe distance between the center of cur%ature and the pole is called radius of cur%ature.

13. REAL IMA'E

The image that can be seen on a screen is -nown as a real image.

14. IRTUAL IMA'E

The image that cannot be seen on a screen is -nown as a %irtual image.

15. MA'NIFICATION

The ratio between the image height and ob ect height is -nown as magnification.

The ratio between the image distance to the ob ect distance is -nown as magnification.REFLECTION OF LI'HT

D$ * *%*,

#The process in which light stri-ing the surface of another medium bounces bac- in thesame medium is -nown as Feflection of Light.#

LA"S OF REFLECTION

;. The angle of reflection, is e*ual to the angle of incidence" nUi mUr.



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6. The incident ray, reflected ray and normal, all lie in the same plane.

KINDS OF REFLECTION

There are two types of Feflection"

1. RE'ULAR REFLECTION

D$ * *%*, @hen parallel rays of light stri-e a surface and most of them are reflected in a same

particular direction or same angle, they are said to be regularly reflected and thephenomenon is -nown as regular reflection.

Fegular reflection occurs when parallel rays of light stri-e with an ideal smooth planesurface. $n regular reflection parallel rays remain parallel after reflection.

(3iagram)

2. IRRE'ULAR REFLECTION

D$ * *%*,

@hen some rays of light stri-es a surface and the reflected rays scatter in differentdirections, this type of reflection is called irregular reflection.

$t occurs when parallel rays stri-e with an irregular rough surface. $n this case raysdoes not remain parallel after reflection and they scattered.

(3iagram)

A % $ , I&&$ 8+ & R$ +$0%*,

3ue to this reflection, sunlight reaches us before sunrise and persists for some timee%en after the sunset.

3ue to this reflection we get sufficient light in our rooms and other places wheresunlight do not reach directly.

3ue to this reflection sunlight reaches to each of the lea%es of a tree andphotosynthesis ta-es place on large scale.

3ue to this reflection, we can see luminous ob ects.

IMA'E FORMED BY A PLANE MIRROR

8onsider a mirror MM:, P is an ob ect. 8onsider that a point P lies on the tip of theob ect. Crom P as ray tra%els and stri-es mirror and reflect bac- to the eye, they appear tocome bac-. Crom Point P: as shown in the figure. Hence P: is the image of P. !imilarly, infinitepoints lying an ob ect produces infinite images of points and complete image of an ob ect isformed.

C> & 0%$&* %*0 , I $ F,& $ ? P+ $ M*&&,& $mage is same in si&e as that of the ob ect.



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The distance of ob ect and image are e*ual from the mirror.The image formed is %irtual and in%erted.

SPHERICAL MIRRORS

D$ * *%*,

# spherical mirror is a section of a of a hollow sphere.#

TYPES OF SPHERICAL MIRRORS

There are two types of spherical mirror"

8onca%e Mirror (8on%erging Mirror)8on%e' Mirror (3i%erging Mirror)

1. CONCA E MIRROR

D$ * *%*,

#The spherical mirror in which inner side of the surface is polished for reflection iscalled a conca%e mirror.#

P&, $&%*$

The bulging side is polished.Feflection occurs from its hollow side.They con%erge the parallel rays at a point.They can form real and imaginary, both types of images.

2. CON E MIRROR D$ * *%*,

#The spherical mirror in which inner side of the surface is polished for reflection iscalled conca%e mirror.#

P&, $&%*$

The bulging side is polished.Feflection occurs from its hollow side.They con%erge the parallel rays at a point.

They can form real and imaginary, both type of images.

FORMATION OF IMA'E BY CONCA E MIRRORS

There are si' cases to form an image by conca%e mirror.

1. OB=ECT AT INFINITY

(3iagram)

$f the ob ect is placed at infinity from the mirror, the rays coming from the ob ect areparallel to principal a'is. fter reflection, they meet at principal focus and image is formed at

the focus.



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D$% *+ , I $

Cormed at C.E'tremely !mallFeal$n%erted

2. OB=ECT BEYOND C

(3iagram)

$f the ob ect is placed beyond 8, rays coming from the ob ect are not parallel. Theymeet after reflection between the focus and center of cur%ature. Therefore, image is formedbetween the focus and center of cur%ature.

D$% *+ , I $

Cormed between C and 8.!mall in si&e.Feal$n%erted

3. OB=ECT AT CENTER OF CUR ATURE JC :

@hen ob ect is placed at the centre of cur%ature, the image formed at the same place.

(3iagram)

D$% *+ , I $ Cormed at 8E*ual in si&eFeal$n%erted

4. OB=ECT BET"EEN F AND C

(3iagram)

@hen the ob ect is placed between the focus and 8entre of cur%ature, the image isformed beyond the centre of cur%ature.

D$% *+ , I $

Cormed beyond 8.Large in si&e.Feal$n%erted

5. OB=ECT AT F



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(3iagram)

@hen ob ect is placed at focus the reflected rays become parallel to each other. Thetwo parallel lines meet at infinity. Therefore, we say the image is formed at infinity.

D$% *+ , I $

Cormed at $nfinity.E'tremely LargeFeal$n%erted

6. OB=ECT BET"EEN P AND F

(3iagram)

Cor locating ob ect between pole and focus the rays reflected do not meet because theydi%erge. ut they meet bac-ward. !o, the image is formed bac-ward or behind the mirror.

D$% *+ , I $ Cormed behind the mirror.Large in si&eDirtualErect

USES OF SPHERICAL MIRROR

!pherical mirrors are used in se%eral places. !ome of them are gi%en below"

S> * ) conca%e mirror is used to enlarge the image.

M*0&, 0, $) con%e' mirror is used for magnification in a microscope.

T$+$ 0, $) The con%e' mirror is used.

I S$ &0>+* >% H$ +* >% ) 8onca%e mirror is used to form the rays insearchlights and headlights, used for different purposes.

F,& R$ & *$


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2. EMER'ENCE AN'LE

The angle formed by the emergent ray and normal is called emergence angle denoted by Ue.

3. OPTICAL CENTER

The middle point of the lens is called optical center. The ray passing through this point doesnot bend.

4. ACCOMMODATION

The ability of the eye to change the focal length of its lens so as to form a clear image of anob ect on its retina is called is power of accommodation.

5. PERSISTENCE OF ISION

@hen an ob ect is seen by an eye, its image forms on retina. $f the ob ect is remo%ed, theimpression of image persists in the eye for about ;


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The refracti%e inde' between two particular mediums is e*ual to the ratio of speed of light infirst medium and speed of light in second medium e*ual to the ratio between sin Ui and sinUr.

R$ & 0%* $ I $ @ * *; * & @ S $$ , +* >% * *& % $ *8 ;S $$ , +* >% *$0, $ *8

PRISM

D$ * *%*,

#Prism is a transparent piece of glass. $t has three rectangular sides and two triangular sides.

R$ & 0%*, T>&,8 > P&*

(3iagram)

where,

Ui angle of incidenceUr angle of refractionUe angle of emergenceU3 angle of de%iation

TOTAL INTERNAL REFLECTION

(3iagram)

$f the %alue of angle of incidence is increased so much so that it becomes greater thanthat of the critical angle then no more refraction occurs but on the other hand refracted rayagain comes bac- in the denser medium. ctually at that time, the surface of denser mediumacts as a plane mirror and the incident ray bends in the same medium. This phenomenon iscalled Total $nternal Feflection. $t is used in Periscope, 4ptical Cibers and other instruments.

T,% + R$ +$0%* P&*

Total internal reflection is used in prism. $n prism the angle between two opposite sidesis =2 and other two angles are ?1 each. $f we arrange a ray so that it falls perpendicular tothe side then it will refract without bending and stri-e the side 8 with angle ?1. Then ittotally reflects to the side 8.

C, *%*, ,& T,% + I %$& + R$ +$0%*,

The ray of light should tra%el from denser to rarer medium.The angle of incidence should be greater than the critical angle.

LENSES

D$ * *%*,



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transparent and smooth glass or any refracting medium surrounded by two sphericalsurfaces is -nown as lens.

TYPES OF LENSES

There are two types of lenses"

1. CON E LENS

$f the glass is thic- at the center and thin at the edges then it is -nown as con%e' lens. $t is acon%erging lens.

(3iagram)

$t has three types"

3ouble 8on%e' LensPlano 8on%e' Lens8onca%o 8on%e' Lens

2. CONCA E LENS$f the lens is thinner in the center and thic-er at the edges then it is -nown as a conca%elens. $t is a di%erging lens.

(3iagram)

$t has three types"

3ouble 8onca%e LensPlano 8onca%o Lens8on%e' 8onca%e Lens

Cormation of $mage by 8on%e' Lens

1. OB=ECT AT INFINITY

@hen ob ect is placed at infinite distance from con%e' lens the rays coming from the ob ectare parallel to each other and they meet after refraction at the focus.

D$% *+ , I $

Cormed at CocusFeal$n%ertedt opposite sideHighly diminished

2. OB=ECT BEYOND 2F

@hen ob ect is placed at some distance from 6C then image is formed between the focus andcenter of cur%ature (6C).

D$% *+ , I $

etween C and 6C4pposite side of Lens



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Feal$n%erted!mall in si&e

3. O $0% % 2F

@hen ob ect placed at center of cur%ature, image is formed at center of cur%ature at the

opposite side.

D$% *+ , I $

Feal$n%ertedt 6C!ame in si&et the opposite side of the Lens

4. O $0% $%


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Large!ame side of lenseyond the ob ect

OPTICAL INSTRUMENTS

1. THE EYE

(3iagram)Cunctions of the Parts of Eye

1. SCLERA SCELORTIC

$t is a layer enclosed in ca%ity filled with a fluid called Ditrous Humour. $t is the outer coatingof eye.

2. CHOROID

$t is a dar- membranous coating. This is coated with blac- pigments. $t -eeps the inner parts

of the eye ball light proof.

3. RETINA

$t is semi transparent membranes of ner%e fibers forming the innermost coating of the eyeand sensiti%e to light. $t is a screen on which image is formed.

4. CORNEA

$t allows light into the eyes. $t is transparent and bulging in shape.

5. IRIS $t is li-e diaphragm of a camera. $t has a tiny opening at its center called pupil, whichregulates the *uantity of light entering the eye.

6. CRYSTALLINE LENS

This is a lens that automatically contracts and e'pands, alters the focal length of eye lens.

7. CILIARY BODY

$t holds crystalline lens in the proper position.

. A 8$,8 H8 ,8& *%&,8 H8 ,8&

The place between cornea and the lens is filled by a transparent li*uid called *ueousHumour. The large chamber of the eye between the lens and the bac- of eye is filled with a

elly li-e substance called Ditreous Humour. These li*uids ser%e mainly to -eep the sphericalshape of the eye.

Main 3efects of Eye

1. SHORT SI'HTEDNESS (MYOPIA!

$f a person can see ob ect placed near, but cannot see distant ob ect, this defect is -nown asshort sightedness.



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C 8 $

This defect appears due to increase in thic-ness of eyeball. The focal length decreasesma-ing the image to form before retina.

(3iagram)

R$ , + , D$ $0%

$t is remo%ed by using a conca%e lens of suitable focal length.

(3iagram)

2. LON' SI'HTEDNESS (HYPERMETROPIA!

$f a person can see distant ob ects, but not near ob ects, this defect is called longsightedness.

C 8 $

This defect appears due to decrease in thic-ness of ball. The focal length increases so that theimage is formed beyond the retina.

(3iagram)

R$ , + , D$ $0%

$t is remo%ed by sing a con%e' lens of suitable focal length.

(3iagram)

3. ASTI'MATISM

$t is the defect in which the clear image of an ob ect does not form on the retina.

C 8 $

This defect appears due to non sphericity of the cornea.

R$ , +

This defect can be remo%ed by using lenses of different focal length.

4. PRESBYOPIA

The accommodation power of eye loses by which a person suffers a long sightedness. Thisdefect is called Presbyopia or Lac- of ccommodation.

C 8 $

This defect appears due to loss of accommodation power of the lens of the eye.

R$ , + This defect can be remo%ed by using con%e' lens.



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2. CAMERA

D$ * *%*,

camera is an optical de%ice for obtaining still photographs or for e'posing cinematic films.

C, %&80%*,

$t consists of a light proof bo' with a lens at one end and a photographic plate or film at otherend and a shutter to control the light rays.

",&/*

To ma-e an e'posure, the shutter is opened and an image is formed by lens on thephotographic plate or film, small in si&e. Photographic plate or film sa%es this image. $n thisway an image is obtained.

3. COMPOUND MICROSCOPE

C, %&80%*,

$t consist of two con%e' lenses at the end of two tubes. 4ne tube can slide into other so thatthe distance between them can be change. The lens near the ob ect is the small con%e' lensof short focal length is called ob ecti%e. The lens near the eye is the larger con%e' of longerfocal length is called eyepiece.

(3iagram)

",&/*

The ob ect is placed between C and GC and its real, in%erted and magnified image : : isformed. The eyepiece is brought close to it so that it comes within its focal length. The firstimage : : acts as an ob ect and a %irtual, erect and magnified final image # # is formed.The magnification of a microscope can be %aried by using different ob ecti%es.

4. ASTRONOMICAL TELESCOPE

$t is used to see hea%enly bodies.

C, %&80%*,

$t consists of two con%e' lenses at the end of the two metallic tubes. 4ne tube can slide intoother so that the distance between can be changed. The lens near the ob ect is a con%e' lensof longer focal length called the ob ecti%e, while the lens near the eye is a small con%e' lensof shorter focal length called the eyepiece.

(3iagram)

",&/*

The rays from distant ob ect entering the ob ecti%e and form a real, in%erted and diminishedimage : : near the principal focus. The eyepiece is ad usted so that the image formed by theob ecti%e comes within its focal length. Thus the eyepiece acts as a magnifying glass and a%irtual, erect and magnified image # # is formed by the first image.



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DIFFERENCE BET"EEN REAL IMA'E AND IRTUAL IMA'E

R$ + I $

;. Feal image is formed when rays after reflection actually meet at a point.

6. Feal image is in%erted and can be seen on a screen.

B. $t has a physical e'istence.

*&%8 + I $

;. Dirtual image is formed when rays do not actually meet but appear to di%erge from a point.

6. Dirtual image is erect and cannot be seen on a screen.

B. $t does not ha%e a physical e'istence.

CHAPTER NO. 15 NATURE OF LI'HT AND ELECTROMA'NETIC SPECTRUM

DEFINITIONS

1. DUAL NATURE OF LI'HT

Light has dual nature, it beha%es not only as a particle (photon) but also as a wa%e. This iscalled dual nature of light.

2. DISPERSION OF LI'HT

@hen a beam of sunlight falls on a prism, the light is split up in se%en colours. Thisphenomenon is called 3ispersion of Light.

3. RAINBO"The rainbow is an arc of spectral colours formed across the s-y during or after rainfall in themorning or when the sun is behind us.

4. PHOTONS ( UANTUM!

Photons are tiny pac-ets of energy. They beha%e as particles but actually they are notparticles.

@@N$$,&? , L* >%@@

This theory which was proposed by Jewton is as follows"

Light is emitted from a luminous body in the form of tiny particles called corpuscles.The corpuscles tra%el with the %elocity of light.@hen corpuscles stri-e the retina they ma-e it sense light.Medium is necessary for the propagation of light.Delocity of light is greater in denser medium.

"A E THEORY OF LI'HT

$n ;A>A, Huygen proposed this theory. ccording to this theory"

Light propagates in space in the form of wa%es.$t can tra%el in space as well as in a medium.Light does not tra%el in a straight line but in sine wa%e form.



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Delocity of light is greater in rarer medium.Medium is not necessary for propagation.

UANTUM THEORY OF LI'HT

ccording to this theory of Ma' Plan-"

Light is emitted from a source discontinuously in the form of bundles of energy calledPhotons or uantum.

$t tra%els in space as well as a medium.

!peed of light is greatest in space or %acuum.

HO" A RAINBO" IS FORMED

s we -now a prism disperses sunlight into a series of se%en colours. @hen rain falls,

raindrops beha%e li-e a prism and white light entering the raindrop splits up into se%encolours on refraction. These are appeared as Fainbow.

SPECTRUM

fter the dispersion of light or any electromagnetic wa%e, a band of colours is formed, whichis -nown as a spectrum.

ELECTROMA'NETIC SPECTRUM

Electromagnetic spectrum is a result obtained when electromagnetic radiation is resol%ed intoits constituent wa%elength.

"A ES OF ELECTROMA'NETIC SPECTRUM

R *, " $

$t has a large range of wa%elengths from a few millimeters to se%eral meters.

M*0&,< $

These radio wa%es ha%e shorter wa%elength between ;mm and B22 mm. Microwa%es areused in radars and o%ens.

I & &$ " $

$t has a long range. $ts mean wa%elength is ;2 micrometers.

* * +$ " $

$t has a range of ?22 nm to >22 nm.

U+%& *,+$% " $

Their wa%elength ranges from B02nm onwards. These are emitted by hotter start (about61222 8).



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CHAPTER NO. 16 ELECTRICITY

DEFINITIONS

1. INSULATORS

Those material ob ects that do not allow charge to pass through them are -nown as$nsulators or non conductors.2. CONDUCTORS

Those material ob ects that allow the charge to pass through them are called conductors.

3. SEMI CONDUCTORS

Those material ob ects that allow some charge to pass through them are called !emi8onductors.

4. FREE ELECTRON

Those electrons that are loosely bound by their atom and can mo%e freely within the materialare called free electrons.

5. DIELECTRIC

The medium or space (%acuum) between two charges is said to be dielectric.

6. FORCE OF ATTRACTION

@hen two charges attract each other the force is called force of attraction. $t has a negati%esign.

7. FORCE OF REPULSION

@hen two charges repel each other the force is called force of repulsion. $t has a positi%esign.

. E UI ALENT RESISTANCE

The relati%e resistance that has e*ual %alue to the combined %alue of a resistor of a circuit iscalled e*ui%alent resistance. $t is denoted by F(E).

9. DIRECT CURRENT

!uch a current that does not change its direction is -nown as direct current. $t is denoted by38, which is obtained from primary and secondary cell.s

1 . ALTERNATIN' CURRENT!uch a current that re%erses its direction with a constant fre*uency from positi%e to negati%eand negati%e to positi%e direction is -nown as lternating 8urrent, obtained by generators. $tis denoted by 8.

11. CON ENTIONAL CURRENT

n electric current considered to flow from points at positi%e terminal potential to points atnegati%e potential.

12. PRIMARY CELL

%oltaic cell in which the chemical reaction that produces the e.m.f is not re%ersible is -nownas Primary 8ell.



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13. SECONDARY CELL

n electric cell that can be changed by passing an electric current through it is called!econdary 8ell. The chemical reaction in this case is re%ersible.

14. FUSED PLU'

$t is a wired plug, which has its own cartilage fuse. $t is used in a ring main circuit.

15. ELECTRIC CIRCUIT

combination of electrical components that form a conducting path is called an electriccircuit.

16. COMMERCIAL UNIT OF ENER'Y (K"H!

; -@h is the energy produced by a resistor or conductor in ; hour when it uses ;222 @attpower.

17. "ATT

$f ; oule of electrical wor- is done in ; second then the power is called ; watt.

ELECTROSTATIC INDUCTION

@hen a charged body brought close to another uncharged body then other body gains somechrge without any touch. This is called electrostatic induction.

'OLD LEAF ELECTROSCOPE

n electroscope is a de%ice that can be used for detection of charge.

JCONSTRUCTION$t consists of a glass case that contains two turn lea%es of gold ( u) which are capable todi%erge. The lea%es are connected to a conductor to a metal ball or dis- out side the case, butare insulated from the case itself.

(3iagram)

",&/*

$f a charged ob ect is brought close to the ball, a separation of charge is induced between theball and gold lea%es. The two lea%es become charged and repel each other. $f the ball is

charged by touching the charged ob ect the whole assembly of ball and lea%es ac*uires thesame charge. $n either case greater the amount of charge greater would be the di%erging inlens.

ELECTROSTATIC POTENTIAL

charged body place in electrostatic field as an electrostatic potential as earth has itsgra%itational potential.

POTENTIAL DIFFERENCE

D$ * *%*,



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#The difference in electrostatic potential between two points in an electrostatic field iscalled potential difference.#

@hen a unit positi%e charge body mo%es against an electrical field from to , thenwor- done has been stored as potential difference. Therefore, we say that

#Potential difference is wor- done or energy stored per unit charge.#

U *%

!ince

Potential 3ifference @or- 3one


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FARAD

$f ; coulomb charge charge produces a potential difference of ; %olt then capacitance is e*ualto ; Carad.

FACTORS

8apacitance of a capacitor depends upon the following factors"

rea of PlatesJature of dielectric3istance between platesJature of metal platesTemperature of 3ielectric and Plates

ELECTROMOTI E FORCE (E.M.F!

measure of the energy supplied by a source of electric current. $t is e*ual to the energy

supplied by the source to each unit of charge.$. . @ E $& ? S8 +*$ ; C> & $

U *%

The unit of e.m.f is %olt.

ELECTRIC CURRENT

T>$ & %$ , +,< , 0> & $ * 0 ++$ $+$0%&*0 08&&$ %.

M %>$ %*0 + F,& ccording to the definition"

Electric 8urrent 8harge


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The unit of resistance is 4hm.

F 0%,& , *0> R$ * % 0$ D$ $

Fesistance 3epends upon the following factors"

A&$ , C&, S$0%*, , C, 80%,&) Fesistance increases when area of crosssection increases.

L$ %> , C, 80%,&) Fesistance increases when the length of conductor isincreased.

T$ $& %8&$) Fesistance in metallic substances is directly proportional totemperature and in non metals is in%ersely proportional to the temperature.

N %8&$ , S8 % 0$) Fesistance also depends upon the nature of the conductor orsubstance.

OHMJS LA"

S% %$ $ %

The current passing through a conductor is directly proportional to the potentialdifference across the end points of the conductor.

M %>$ %*0 + F,&

ccording to this law"

D U $ (U represents the sign of proportionality. 3o not write this in your e'amination paper)

I @ IR

@here F is a constant is called the resistance of the conductor.

RESISTOR

The body or thing that offers resistance in an electrical circuit is -nown as resistor. Theappliance or de%ice that wor-s on the presence of electric current is -nown as resistor.

COMBINATION OF RESISTORS

1. IN SERIES

@hen resistors are combined in series, they ha%e the following properties"

8urrent passes through all resistors has e*ual %alue, i.e. $ $; $6

Doltage is different according to the resistance.

Total %oltage is e*ual to the combined %oltage or the sum of the %oltages of allresistors, i.e. D D; D6 DB

Total resistance is e*ual to the sum of all the resistances, i.e. FE F; F6 FB



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D$&* %*,

(3iagram)

s show in the abo%e diagram and according to the properties of combination.

D D; D6 DB

but D $F and D; $F;, D6 $F6 and DB $FB, therefore"

$F(E) $F; $F6 $FB

$F(E) $ (F; F6 FB)

R(E! @ R1 R2 R3

2. IN PARALLEL

@hen resistors are combined in parallel then this combination has the following properties"

8urrent has different ways to pass through.8urrent has different %alue in each resistor according to its resistance.Total current is e*ual to the algebraic sum of each current, i.e.e $ $; $6 $BPotential difference (Doltage) is same across each resistor, i.e. D D; D6 DBFesistance is small or less than all combined resistance.Total resistance is gi%en by the formula ;


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D*&$0% C8&&$ %

;. 38 is obtained by connecting the two ends of a conductor to the terminals of a batter.

6. $ts direction remains unchanged.

Documents

Second Physics Notes