Magnetic Effect and Magnetism

7/23/2019 Magnetic Effect and Magnetism

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Magnetc Effects and Magentism Very Short answer Type QuestionsQ.1 State Amperes circuital lawAns. Ampere Circuital law states that the line integral of magnetic field B around any closed path in vacuum is

equal to 0times the total current threading the closed path i.e.

0.B dl I=

It is independent of the size and the shape of the closed curve enclosing the current.

Q.! State "iot Sa#arts $aw

Ans. It states that the magnetic field produced by a small currentelement I, dlat a point at distance r is given by

sinIdldB k

r

=

In !ector "orm

0

# #$

Idl r Idl rdB k

r r

= =

uur

Q.% &efine an ampere in terms o the force 'etween current carrying conductors.

Ans(

0 % %

I IF F

r

= =

&&&'i(

)ubstituting I%* I* %A, r *% m in 'i(

+0%

%0

F F F N

= = = =

)o one ampere is the current which when through to infinitely long conductors separated by a distance of

%m eerts a force of %0 &+m.

Q.) &efine *ersted rule or Snow rule.Ans. According to this rule if electric current flows from )&pole towards -&pole over a freely suspendedmagnetic needle then -& pole of the needle will deflect towards the west.

Q.+ ,hat will 'e nature of magnetic field produced 'y infinitely long current carrying conductor-

Ans. he magnetic field will be circular in nature,i. e.,the magnetic lines of force will be in the form ofconcentric circles with the conductor as centre the conductor will be perpendicular to the plane of

magnetic lines of force. he direction of magnetic field can be determined by applying right hand thumb

rule.

Q. &efine Ampere/s swimming rule.Ans. According to this rule, if we imagine a man swimming along the wire in air in the direction of current with

hisface always turned towards the needle, so that the current enters at his feet and leaves at his head, thenthe -&pole of the magnetic needle will be deflected towards his left hand.

Q.0 &efine one Tesla. *r

&efine unit of magnetic field intensity.Ans. esla is the unit of magnetic field intensity in ).I. system of units.he force applied by a magnetic field of

strength B on a chargemoving with velocity# is given by the relation," *"#sin /00 B *23#sin /00

et* % C,#* % m1s,* /00, " * I-

% %

0

% %% %

%% ' /0 (

N NsTesla NC m

m CmC Sin

s

= = =

4ence magnetic field intensity is said to 'e one tesla if a charge of one coulom' mo#ing at right

angle to the field with a #elocity one metre per second e5periences a force one newton.


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Q.6 ,hat is meant 'y magnetic $orent7 forceAns. 2agnetic orentz "orce3 he force eperienced by a charged particle, when moving inside the magnetic

field is called magnetic orentz force and is given by

' (F q v B=

Q. 8 9yclotron is not suita'le for accelerating electrons. E5plain ,hyAns. 2ass of electron is very small. It suffers a very large increase in velocity under the action of electric field.

4ue to the increase in velocity, relativistic mass increases and thus decreasing optimum required

frequency. and it get out of step with electric field soon. 56

It is based on the principle that positively charged particles can acquire high energy when they arerepeatedly passed through an alternating electric field along a closed path ma7ing use of perpendicular

magnetic field.

Q.1: ,rite the e5pression for the force acting on charged particle mo#ing in the magnetic field.Ans. he force eperienced by a charged particle, when moving inside the magnetic field is called magnetic

orentz force and is given by

' (F q v B=

8here q * charge on the particle, v* velocity of charged particle, B * Applied magnetic field.

Q.11 ;nder what condition an electron mo#ing in a magnetic field e5periences a ma5imum force Ans. he force eperienced by an electron moving in a magnetic field is given by the relation,

" *q vB sin

-ow, " will be maimum when * /09 'v sin /09 * % * ma.( :lectron will eperience the maimumforce when it moves at right angle to magnetic field.

Q.1! ,hat is the direction of force acting on the charged particle mo#ing with a #elocity # in themagnetic field "

Ans. he direction of force on the charged particle moving with velocity v in magnetic field B is given by"leming eft ;and rule. It states that if the fore finger, central finger and the thumb of left are stretched

mutually perpendicular to each other such that the fore finger points in the direction of magnetic fieldB

,

the central finger points in the direction of current, then thumb will point in the direction of force

eperienced by the conductor. hen according to this rule the direction of force will be perpendicular to

the plane containing v and B.

Q. 1% A particle of charge mo#ing with a #elocity # at an angle to magnetic field ". ,hat is the force

e5perienced 'y the particleAns. he force eperienced by a charged particle, when moving inside the magnetic field is called magnetic

orentz force and is given by

' (F q v B=

" *q vB sin

8here q * charge on the particle, v* velocity of charged particle, B * Applied magnetic field.

Q.1) &efine 2leming


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If angle between

dland

Bis /00and sin /00* %2aimum force " * BIl

2inimum "orce " * 0 If * 00and sin 00* 0

4irection 3 he direction is given by "leming left hand rule. According to figure, the force will be directed

upwards in the plane of paper.

Q.10 State the principle of mo#ing coil gal#anometerAns. 2oving coil galvanometer is based on the principle that when a current carrying conductor is placed in a

magnetic field, it eperiences a torque.

Q.16 ,hat is shunt State its S= unit.Ans. A calculated low resistance connected in parallel to a device to bypass the surplus current is to save the

electrical instrument is called shunt. It is measured in ohm.

Q.18 State two properties of a 'ar magnet.Ans. %. i7e poles repel each other < unli7e poles attracts each other

. A magnet attracts magnetic substance

#. A freely suspended magnet always come to rest alone -&) direction.

$. A bar magnet has no strength at its centre.

=. If a bar magnet is divided into a number of pieces, each piece will be a complete magnet.

Q. !:. &efine neutral point in a magnetic field.Ans. It is that point in a magnetic field where the intensity of earth magnetic field is equal to and opposite to the

magnetic field intensity of the given magnet so that net magnetic field at this point is zero.

Q. !1 ,hat is 'asic difference 'etween electric and magnetic fields Ans. '%( :lectric field is produced by both stationary and moving charges, whereas magnetic field is produced

only by a moving charge.

'( :lectric field lines are discontinuous whereas magnetic field

lines are continuous.

Q .!! &efine dipole moment of a magnet.Ans. he product of pole strength of either pole of a magentic dipole and length of dipole is called dipole

moment.Ifmis the pole strength and lis length of dipole then dipole moment,

pm* m l = 2ml.

Q.!% &efine angle of Magnetic dip.Ans. Angle of dip at a place is the angle between the direction of total intensity of earth>s magnetic field and the

horizontal direction in the magnetic meridian.

At 2agnetic poles * /00 At 2agnetic equators * 00

Q.!) E5plain three magnetic elements of earths magnetic field at a gi#en place.Ans. :arth has three magnetic elements

'%( 4eclination '( 4ip or inclination '#( ;orizontal component of the earth>s field

&eclination(It is defines as the angle between the magnetic meridian and the geographic meridian at a

palce. It is denoted by angle .

&ip or inclination(4ip at a place is defined as the angle between the direction of the total intensity of the

earth>s magnetic field and a horizontal line in the magnetic merdian.

4ori7ontal 9omponent >4?(he total intensity of the earth>s magnetic field at any point can be resolved

into two rectangular components one along the horizontal and the other along the vertical direction. he

component of the resultant intensity of the earth>s magnetic field in the horizontal direction in magnetic

meridian is called its horizontal component. It is denoted by ;. he component of the resultant intensity of

the earth>s magnetic field in the vertical direction in magnetic meridian is called its vertical component. It

is denoted by !.

Q. !+ &efine "ohr magneton.

Ans. It may be defined as the orbital magnetic moment of an electron revolving in the innermost orbit 'n*%(


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%? #$ #%

%? #$$

#%

$

%.? %0 , ?.? %0 , /.% %0

%.? %0 ?.? %0 +/.+ %0

$ /.% %0

B

e

e

B

eh

m

e C h Js m kg

Am

= =

= = =

= = =

Q.! ,hat do you mean 'y pole of a 'ar magnet

Ans. @ole of bar magnet it represent the strength of the magnetic field. It is termed as pole strength and is given by

m * pm1l

Q.!0 &efine magnetic inclination.

Ans. 4ip or inclination3 4ip at a place is defined as the angle between the direction of the total intensity of the earth>s

magnetic field and a horizontal line in the magnetic meridian.

Q.!6. &efine magnetic declination.

Ans. 2agnetic 4eclination3 It is defines as the angle between the magnetic meridian and the geographic meridian at a

palce. It is denoted by angle .

Q.!8. ,hat is a magnetic dipole

Ans. It consists of two poles of equal and opposite strength separated by a fied distance called dipole length l.Q.%1 @ame the physical uantity which is measured in we'er ampere1.Ans. he physical quantity which is measured in weber ampere &%is

)elf inductance or coefficient of self induction '(.

Q.%! ,hat is the 'asic cause of induced e.m.f. Ans. he basic cause of induced emf in a coil is the change in magnetic flu lin7ed with the coil.Q.%% ,hat is meant 'y magnetic flu5 Stale its S.=. unit.Ans. he total no. of magnetic lines of force lin7ed with the surface is called

magnetic flu lin7ed with that surface. "or defining magnetic flu lin7ed with thesurface we ta7e area as area vector 'also called surface vector(. "or a plane surface

having area A then A * n A where n is the unit vector drawn

perpendicular to the surface. hen magnetic flu lin7ed with the surface

is* B . A * BAcos

8here is the angle between the normal to

surface area and magnetic field.

he flu lin7ed with surface is minimum '* 0( when surface is placed parallel to magnetic field the angle

between the normal and magnetic field is /00.

he flu lin7ed with surface is maimum '* BA( when surface is placed perpendicular to magnetic field

then the angle between the normal and magnetic field will be 00.

Q.%) &efine ,e'er unit of magnetic flu5.Ans. nits of magnetic flu in )I is weber '8b(.

* B . A * BAcos

If B* %esla, A * %m, *00

% wb * % tesla m

5ne 8eber is amount of magnetic flu over an area of %mheld normal to uniform magnetic field of one

tesla.

4imensional formula3 2&A&%

Q.%+ ,e'er is unit of which physical uantityAns. 8eber is unit of magnetic fluQ.36 State two properties of ferromagnetic substances.Ans. '%( 8hen a piece of such a substance is placed in a non&uniform magnetic field, it moves from wea7er to

stronger part of the field.

'( If a bar of such a substance is suspended in a uniform magnetic field, it sets itself parallel to the

magnetic field.

Q.%0 State two properties of diamagnetic su'stances.


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Ans. 'i( 8hen a piece of diamagnetic substance is placed in a non&uniform magnetic field, it tends to movefrom stronger part to the wea7er part of the field.

'ii( 8hen a rod of such a material is suspended in a uniform magentic field, it sets itself at right angle to

the direction of magnetic field.

Q.%6 State two properties of paramagnetic su'stances.Ans. 'i( 8hen a piece of such a substance is placed in a non&uniform magnetic field, it tends to move from

wea7er part to stronger part of the field.'ii( If a rod of such a substance is suspended freely in a uniform magnetic field, it rotates itself to be

parallel to the direction of magnetic field.

Q.39 State two methods to destroy the magnetic strength of a magnet.Ans. he&strength of a magnet can be destroyed by the following methods.

'i( By heating the magnet till it becomes red hot.

'ii( By beating the magnet with a hammer for a number of times.

Q.40 @ame one metal each to maBe a permanent and a temporary magnet.Ans. 2etal to ma7e a permanent magnet * )teel

2etal to ma7e a temporary magnet * )oft iron.

Q.)1 &efine permea'ility of magnetic su'stances.Ans. @ermeability of a magnetic substance is defined as the ratio of the magnetic induction 'B( to the

magnetizing field ';(.

B

H=

Q.)! ,rite the dimensional formula for magnetic flu5.Ans. 4imensional formula3 2&A&%Q.)% Mention two properties of alloys from which permanent magnets are made.Ans. %. It should be having high corecivity.

. It should be having sufficient retentivity.

#. It should be having strength to with stand high stress.

Q.)) &efine 9uries law in magnetism.Ans. Curie>s law state that the magnetic susceptibility of paramagnetic materials is inversely proportional to its

absolute temperature.

Q.)+ ,hy do magnetic lines of force prefer to pass through iron than through air Ans. Iron being ferromagnetic has larger permeability than air and hence magnetic lines of force prefer to pass

through iron than through air.Q.) ,hat happens to the diamagnetic su'stance when it is placed in nonuniform magnetic fieldAns. 8henever diamagnetic substance when it is placed in non&uniform magnetic field it gets displaced from

stronger to wea7er par of magnetic filed.

Q.)0 &efine &iamagnetic su'stances Ci#e one e5ample.Ans. &iamagnetic3 hose substances, which when placed in a magnetic field, are feebly magnetised in a

direction opposite to the direction of magnetising field are called diamagnetic substances. 8hen such asubstance is placed in a non&uniform field, it tends to move from stronger field to wea7er part of the field.

)ome of the diamagnetic substances are 3 zinc, water, bismuth, copper, sodium chloride etc.

Q.)6 &efine Daramagnetic su'stances Ci#e one e5ample.Ans. @aramagnetic 3 hose substances which when placed in a magnetic field, are feebly magnetised in the

direction of magnetic field, are called paramagnetic substances. 8hen such a substance is placed in a non&

uniform field, it tends to move from wea7er part to stronger part of the field. )ome of the paramagneticsubstances are 3 sodium, aluminium, liquid oygen, copper chloride, platinum and antimony etc.

Q.)8 &efine 2erromagnetic su'stances Ci#e one e5ample.Ans. 2erromagnetic3 hose substances, which when placed in a

magnetic field, are strongly magnetised in the direction of magnetic field, are called ferromagnetic

substances. 8hen such a substance is placed in a non&uniform magnetic field, it moves from wea7er part

to stronger parts of the field. )ome of the ferromagnetic substances are 3 iron, steel, cobalt, nic7el, alnico,

etc.

Magnetic 2ield and Magnetism@umericals1. The electron of the hydrogen atom mo#es along a circular path of radius :.+ 5 1:1:m with a speed of !.! 5 1:

ms1. ,hat magnetic field does it produce at the centre of circular path Ans. r * 0.= %0&%0m , v* . %0?m1s , q* %.? %0 &%/C


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# ?

%/ %0

/.% %0 . %0%$.%

%.? %0 0.= %0

mvB

qr

= = =

T

!. A circular coil of wire consisting of 6: turns- each of radius 6 cm- carries a current of :.+ A. 9alculate themagnitude of magnetic field /"/ at the centre of coil.Ans. n * D0, r * Dcm , I * 0.=A, B *E

+0

$

0.=D0 %0

$ + D %0

#.%$

B nr

T

= =

= 10

+0 %0$

=

Q

%.A Solenoid of length %: cm- ha#ing 1+: turns carries current of !.1 A. 9alculate the magnitude of magneticfield in the interior of the solenoid.Ans. l* #0 cm , n * %=0, I * .%A

+#0 %0 %=0 .%$ %.# %0

+ 0.#

nIB T

l

= = =

+0 %0$

=

Q

). A circular coil of wire consisting of 1:: turns- each of radius 0.6 m carries a current of :.) A. 9alculate themagnitude of magnetic field /"/ at the centre of the coil.Ans. n * %00, r * +.D m , I * 0.$A, B *E

+0

?

0.$%00 %0 $ + +.D %0

#.

B nr

T

= = = 10

+0 %0$

=

Q

+. A solenoid of length of !+ cm- ha#ing 1+: turns carries a current of !.) A. 9alculate the magnitude ofmagnetic field at one end of the solenoid.

Ans. l* =cm, n *%=0, I * .$ A

2agnetic field as one end of solenoid *

0

nI

l

B *

+ #%

$ %0 %=0 .$ 0./0$ %0 + .=

T =

?. A circular coil of wire consisting of 8: turns- each of radius 0.8 cm- carries a current of :.)+ A. 9alculate themagnitude of magnetic field /"/ at the centre of the coil.Ans. )ame as $thFuestion.

0. A circular coil of !:: turns and radius :.! m carries a current of 1) A. ,hat is the magnitude of magneticmoment associated with the coil Ans. n * 00, r * 0.m, I * %$ A, 2 *E

2 * n I A * n I 'Gr( * 00

%$

#.%$

'0.(* #=

%0 Am

6. A current of 1+A flows through a coil of +.: cm radius as shown in figure. 2ind out the direction andmagnitude of magnetic field Bt the centre of the arc. Ans. I * %= A, r * 0.= cm

2agnetic field due to circular ring at its centre *

0

B

r

=

4ue to half ring *

H 0%

B

r

=

*

+% %0 %=

$ + 0.0=

* /.$

%0&=


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8. A cyclotron/s oscillator freuency is 1: M47. ,hat should 'e the operating magnetic field for acceleratingprotons =f the radius of its dees is : cm- what is the Binetic energy >in MeV? of the proton 'eam produced'y the cyclotron Ci#en ( Mass or proton F 1.0 5 1:!0Bg.Ans. n * %0 2;z * %0?s&%, r * ?0cm , .:. * E , B * E , m* %.?+ %0&+7g

% 2e! * %.?0 %0&%#J , q * %.?

%/%0 C

( ) ( )( )++%/ %/

%.?+ %0 %.?+ %0

%.? %0 ?0 %0 %.? %0 ?0 %0

r nrwmvB

qr

= = =

+ ?

%/

%.?+ %0 %0 %0

+

%.? %0 ?0 %0

60 10 =

* 0.?=? * 0.??

( ) ( )

+ ?

% % %

%.?+ %0 '0.?( ' %0 %0 (

+

mv m r w mr n

= = =

=

As % 2e! * %.?0 %0&%#J % J *

%#

%

%.?0 %02e!

%#

%#

%%.D+ %0+.D$

%.?0 %0 !e" !e"

= =

1:. A cyclotron/s oscillator freuency is 11 M47. ,hat should 'e the operating magnetic field for acceleratingprotons =f the radius of its dees is : cm- what is the Binetic energy >in MeV? of proton 'eam produced 'ythe cyclotron Ci#en ( Mass of proton F 1.0 5 1:!0BgAns. n * %0 2;z * %0?s&%, r* ?0cm , .:. * E, B *E,m* %.?+ %0&+7g

% 2e! * %.?0 %0&%#J , q * %.?

%/

%0 C

( ) ( )( )++%/ %/

%.?+ %0 %.?+ %0

%.? %0 ?0 %0 %.? %0 ?0 %0

r nrwmvB

qr

= = =

+ ?

%/

%.?+ %0 %% %0

+

%.? %0 ?0 %0

60 10 =

* 0.+?

( ) ( )

+ ?

% % %

%.?+ %0 '0.?( ' %% %0 (

+

mv m r w mr n

= = =

=

As % 2e! * %.?0 %0&%#J % J *

%#

%

%.?0 %0

2e!

%#

%#

%$.##D= %0/.%D$

%.?0 %0 !e" !e"

= =


8/12

11. A charge 6 coulom' is mo#ing with #elocity

'+ $ ( 1 ,v # k m s

= +r

magnetic field

'+ $ (B # k w$m

= +ur

,'nrr!.2ind the force acting on the charge.

Ans. q * DC,

'+ $ ( 1 ,v # k m s

= +r

'+ $ ( , EB # k w$m F

= + =ur ur

' (F q v B= D '+ $ ( '+ $ ( D D' (# k # k i i

= + + = + * 0

' ()i G#K( ms&%in a magnetic field " F'$i L #K( 8bm&. 2ind theforce acting on the charge. Ans.)ame as %%thFuestion

1%. An electron enters a magnetic field of +T intensity with #elocity + 51:ms1at angle %:H with the direction offield. 2ind the magnitude of force acting on electron.

Ans. B * = , v * =

%0? m1s, M*#00, " * E, q * %.?

%0&%/C

' (F q v B= * qvB sinM*%.? %0&%/ = %0? = sin#00* %0&%-1). An electron enters a magnetic field of )T intensity with #elocity 0.+ 51:ms1at an angle %:H with the

direction of magnetic field. 2ind the magnitude of force acting on electron.

Ans. B * $ , v * +.=

%0? m1s, M*#00, " * E, q * %.?

%0&%/C

' (F q v B= * q v B sinM *%.?

%0&%/

+.=

%0?

$

sin#00* .$

%0&%-

1+. A proton enters a magnetic field of )T intensity- with #elocity !.+ 5 1:msI1at an angle %:H with the directionof field. 2ind the magnitude of force acting on proton.Ans. )ame as %#thFuestion

1. The magnitude of #elocities of two Alpha particles A and "- entering a uniform magnetic field

perpendicularly- are in the ratio (1. *n entering the field- they mo#e in circular paths. 2ind out the ratio ofradii of their paths.

Ans.

?

%

A

B

" qBr "

" m= =

" r

r "

?

%

A A

B B

r "

r "= =

10. An electron >with charge 1. 5 1:189? mo#ing at right angles to a uniforms magnetic field completes acircular or'it in 1:JK sec. 9alculate the #alue of magnetic field.

Ans. q * %.?

%0&%/C , B * E , M* /00, * %0&?sec , m * /

%0% 7g

#%

=

%/ ?

/ %0

+ #.=+ %0%.? %0 %0

mB T

qT

= = =

16. A particle carrying a charge +p9 is mo#ing with a #elocity # F >)i G %B? ms1in a magnetic field " F >%L G)i? w'nT!. 9alculate the force acting on the particle.Ans. )ame as %%thFuestion

18. A particle carrying a charge Sp9 is mo#ing with #elocity # F >!%B?msN1in a magnetic field " F >! %B?w'rrr!. 2ind the force acting on the particle.Ans. )ame as %%thFuestion


9/12

!:. A proton enters into a magnetic field of intensity +51:!Tesla with #elocity of 1:+ms1at an angle %:H with thefield. 9alculate the magnitude of force acting on the proton due to this field.

Ans. B * =

%0& , v * %0= m1s, M*#00, " * E, q * %.?

%0&%/C

' (F q v B= * q v B sinM *%.?

%0&%/

%0=

=

%0&

sin#00* $

%0&%?-

!1. An electron enters into a magnetic field of intensity )51:% Tesla with #elocity of +51:ms1at an angle %:Hwith the field. 9alculate the magnitude of force acting on the electron due to this field.Ans. )ame as %stFuestion

. )ame as %stFuestion!%. An ion of mass 1.651 :!0Bg carrying a charge !51:19 O 'eing accelerated through a potential difference of

!::V enters a unif magnetic field of intensity !51:%Tesla perpendicular to its directio motion. 9alculate theradius of path descri'ed 'y the ion.

Ans. m * %.D

%0&+7g, q *

%0&%?C, @otential N!>*00!, B*

%0, M*/00

%

mv q" =

where v=velocity%?

+

%# ?

%0 00

%.D %0

D%0 ?.?? %0 1

%.D

q"v

m

v m s

= =

= =

+ ?

%? #

%.D %0 ?.?? %0# %0

%0 %0

mvr m

qB

= = =

!). An ion of mass 1.651:!+Bg carrying a charge )51:19 O 'eing accelerated through a potential difference of)::V enters a unif magnetic field of intensity !51:!Tesla perpendicular to its directio motion. 9alculate theradius of path descri'ed 'y the ion.Ans. )ame as $thFuestion

!+. An ion of mass 1.651:!8Bg carrying a charge !51:N after 'eing accelerated through a potential difference of

1:: V ente uniform magnetic field of intensity 1:%

Tesla perpendicular to its direc of motion. 9alculate theradius of path descri'ed 'y the ion.Ans. )ame as $thFuestion

!. A Cal#anometer of +: ohm resistance shows full scale deflection for a current of !mA. 9alculate shuntresistance needed to con#ert it to an ammeter of range :.+ A.Ans. O * =0P, Ig* mA, ) *E, I * 0.=A

#

#

%0'=0( 0.

0.= %0

g

g

IS %

I I

= = =

in parallel with galvanometer.

!0. The Cal#anometer of 6: ohm resistance gi#es full scale deflection for a current of ):5 1:)A. 4ow will youcon#ert it into a #oltmeter of range :.+ V Ans. O* D0 P, Ig* $0Q%0

&$A,!* 0.= !, 6*E

0.=D0 $=

0.00$

g

g

"I

% &

"& %

I

=+

= = =

in series with galvanometer


10/12

!6. A short conductor of length +.: cm is placed parallel to a long conductor of length 1.+ m near its centre. Theconductors carry a current of )A and %A respecti#ely in the same directions. ,hat is the total forcee5perienced 'y long conductor- when they are separated 'y % cm in #acuum Ans. I * =.0 A, " * Q%0&$-, r *E

?% %

%0 + # $0.0= $ %0

0.0#

'I I

F l Nr

= = =

!8. A long straight wire P carries a current of ! amperes. Aproton @ travels at= %0&?msN1- parallel to the wireas shown in the diagram- :.! m away from it. 2ind out the magnitude and direction of force which magnetic

field e5erts on the proton.

Ans. I * A, v * =Q%0&?m1s, r * 0. m, q * %.?

%0&%/C+

?0 %0

%0$ 0.

IB T

r

= = =

' (F q v B= * q v B sinM *%.?

%0&%/

=

%0&?

%0&?

sin/00* %.?

%0-

%:. A Cal#anometer has a resistance of +: *hm. A resistance of + *hm is connected across its terminals. ,hatpart of total current will flow through the gal#anometer Ans. C F +:R- S F +R- =gF

( )= =0

%0

%%

%

%%

g

g

g

g

g g

g

g

IS %I I

I

I I

I I I

I I

I I

=

=

=

=

=

%1. A Cal#anometer coil has a resistance of 1+ *hm and the meter shows full scale deflection for a current of)MA. 4ow will you con#ert the meter into an ammeter of range : to A Ans. O *00P, ) * E, Ig* $mA, I * ?A

=/=

%00 ==

%00

g

g

IS %

I I

I

S

I I

=

= =

%!. A #oltmeter reads upto %V. =ts resistance is !:: *hrn. =t is to 'e used to measure a potential difference whichmay 'e as large as :V. ,hat measure you would taBe to protect the #oltmeter Ans. ! * #!, O *00P, !>*?0!

#

00gI A=

?000 #D00

#

00g

"& %

I

= = =

in series


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%%. =t is desired to pass only + of the current through a gal#anometer of resistance 8+Q. ,hat shunt resistanceshould 'e connected across it

Ans.

=

%00gI I=

, O * /=P, ) * E

=/=

%00 ==

%00

g

g

IS %

I I

IS

I I

=

= =

%). A resistance of 8:Q is connected in series with a gal#anometer of resistance 1::Q. A potential difference of1V produces a deflection of 1:: di#isions in the gal#anometer. 2ind the figure of merit gal#anometer.Ans.6 * /0P, O * %00P, ! * %!, n * %00

$

% %

$$ =0 =0 %0

+ +

0.%0%# %0%.#

(n C

H mH

= =

= =

"igure of merit *

#==. %0 =. %0 1

%00

gIA divisi'n

n

= =

%+. A short 'ar magnet has a magnetic moment of :.!)3T. 9alculate the magnitude of magnetic field produced'y magnet at a distance of 1:cm from the center of the magnet on the a5is of magnet.Ans. pm * 0.$J1 , r * %0 cm * 0.% m

( )

0

#

$

mp rB

r )

=

, "or )hort Bar 2agnet

( ) ( )

+=0

##

%0 0.$$.D %0

$ 0.%

mpB Tr

= = =

%. A short 'ar magnet has a magnetic moment of :.!3T. 9alculate the magnitude of magnetic field produced'y magnet at a distance of 6cm from the center of the magnet on the a5is of magnet.Ans. )ame as #+thFuestion.


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Magnetic Effect and Magnetism