Sr Physics - Chapter Wise Important Questions

Page No. 33

VanithaTV GUIDE education & Career SR Inter - Maths Physics Chemistry

PHYSICS BLUE PRINIT

Units Name of the chapter Weightage marks

Wave Motion 08

Ray optics and optical Instruments 04 I.

Physical optics 04

II. Magnetism 06

Electrostatics 06

Current electricity 08 III.

Thermo-electricity 04

IV. Electro magnetics 12

Atomic physics 06

Nuclear physics 08

Semi-conductor devices 08 V.

Communication systems 02

Total marks 76

QUESTION BANK ANALYSIS

L.A.Q. S.A.Q S.NO

NAME OF THE

CHAPTER *** ** * *** ** * V.S.A.Q PROBLEMS

1 WAVEMOTION 5 1 - 5 3 1 15 12

2 RAY OPTICS - - - 7 2 3 17 5

3 PHYSICAL OPTICS - - - 6 2 - 7 1

4 MAGNETISM - - - 4 3 2 9 4

5 ELECTROSTATICS - - - 5 2 1 14 5

6 CURRENT

ELECTRICITY 2 3 - 1 2 - 9 2

7 THERMO

ELECTRICITY - - - 4 - - 1 2

8 ELECTRO

MAGNETICS 5 - 1 3 3 - 9 5

9 ATOMIC PHYSICS - - - 4 1 - 6 2

10 NUCLEAR PHYSICS 1 1 - 3 2 4 7 1

11 SEMI CONDUCTOR

DEVICES 2 - - 3 2 1 4 1

12 COMMUNICATION

SYSTEMS - - - - - - 5 -

SUB TOTAL 15 5 1 45 22 12 103 40

TOTAL 21 79 103 40

SENIOR INTER PHYSICS

IMPORTANT QUESTION BANK By Srigayatri

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WAVE MOTIONLONG ANSWER QUESTIONS

1***. Explain the formation of stationary waves in stretched strings and hence deduce thelaws of transverse waves in stretched string (Mar, 2009)

2***. State laws of transverse vibrations in stretched strings. Explain how do you verifythem using sonometer. (Mar, 2005, 2007)

3***. What are “Harmonics” and Overtones”? How are they formed in an open pipe?Derive the equations for the frequencies of the harmonics produced in an open pipe.

4***. What are harmonics? How are stationary waves formed in a closed pipe? Explian thevarious modes of vibrations in a closed pipe and establish the relation between theirfrequencies? ( May, 2009)

5***. What is Doppler effect? Find an expression for the apparent frequency heard whenthe source is in motion and the listener is at rest. What is the limitation of Dopplereffect? (M 2006)

6**. What is Doppler’s shift? Derive an expression for the apparent frequency heard by amoving listener when the source of sound is at rest. What is the effect of the movingmedium on the Doppler effectSHORT ANSWER QUESTIONS

1***. What are beats? Explain the importance of beats.2***. What are applications of ‘ Doppler Effect’?3***. Define “Absorption coefficient” and Reverberation time”. State and explain Sabine’s

formula for reverberation time in a closed auditorium. (Mar, 2008)4***. Define an echo. What is the minimum distance required to form an echo. Write its

application (Mar, 2006)5***. Write the condition for the construction of good auditoria.6**. Explain the reflection of waves at closed and open ends.7**. Explain the characteristics of a sound note.8**. What is Resonance? Explain with an example.9*. What is Doppler effect? Derive an expression for the apparent frequency of a note,

when source of sound and observer are approaching each other.RAY OPTICS

SHORT ANSWER QUESTIONS10***. What is total internal reflection? State the conditions to be fulfilled for total internal

reflection11***. Describe the construction and working of an optical fibre. Sate its uses. (M06, 08)12***. Distinguish between an astronomical telescope and a terrestrial telescope.13***. Describe Rams dens’ eye piece with the help of a neat sketch. Explain its advantages

and disadvantages (Mar, 2009, 2007)14***. Describe Huygens eye piece with the help of a neat sketch. Explain its advantages and

disadvantages.15***. What are pure and impure spectra. State the conditions to produce a pure spectrum.16***. With the help of a ray diagram, illustrate the formation of the final image of an object in

a compound microscope. Derive an expression for its magnifying power.17**. What are lens aberrations? Give reasons for them.18**. Explain the working of a simple microscope and find an expression for its magnifying

power.19*. What is dispersion? Define a physical quantity which depends only on the material of

the prism for its dispersion. Obtain an expression for it.20*. State the significance of emission and absorption spectra.21*. Derive the expression for refractive index of material of the prism.

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PHYSICAL OPTICSSHORT ANSWER QUESTIONS

22***. Write about the main features in which Fraunhoffer and Fresnel approaches of diffractiondiffer?

23***. Mention some (at least four) applications of diffraction (March, 2007, 2005)24***. What the applications of polarization of light? (March, 2008)25***. Write any four applications of interference of light (March, 2009)26***. Explain how plane polarized light obtained by reflection. (M2005, M2006,M 2009)27***. Explain how plane polarized light obtained by refraction.28**. Explain double refraction ( birefringence) of light.29**. Describe Young’s double slit experiment and give the necessary theory to explain

formation of dark and bright interference pattern (March, 2006 , 2008)MAGNETISM

SHORT ANSWER QUESTIONS30***. Derive the equation for the couple acting on a bar magnet in a uniform magnetic field

and hence deduce the definition of magnetic moment (M06, 2008, 2009, May, 2006)31***. Derive an expression for the period of oscillation of a bar magnet in vibration

magnetometer.32***. How do you distinguish Dia, Para and Ferromagnetisms in matter.33***. Derive an expression for the magnetic induction at a point on the axial line of a bar

magnet. (March, 2009)34**. Derive an expression for the magnetic induction at a point on the equatorial line of a

bar magnet.35*. Explain ‘tan A ‘and ‘tan B’ positions of a deflection magnetometer. (March, 2009)36**. Explain the theory to determine magnetic moment of a bar magnet and Horizontal

component of the earths magnetic induction BH at a place.

37*. State and explain “Tangent law” in magnetism.38*. Compare magnetic moment of two bar magnet in a tan A, tan B position by equal

distance method or null method.ELECTRO STATICS

SHORT ANSWER QUESTIONS39***. Define a) Intensity of electric field E, B) Potential difference between two points V.

Derive the relation between them. (March, 2009)40***. Define capacitance or capacity of a conductor and explain the principle of capacitor.41***. Derive the equation for equivalent capacitance (Capacity) When a number of capacitors

are connected in parallel.42***. Derive equation for the equivalent capacitance (Capacity) when capacitors are connected

in series. (March, 2008, May, 2009)43***. Derive an expression for the energy stored in a capacitor. What is the energy stored

when the space between the plates is filled with a dielectric a) With charging battery disconnected b) With charging battery connected in the circuit. (M09, 07, 05, 2006, May, 2006)44*. Write a note on different types of capacitors.45*. Applying Gauss’s law derive the expression for electric intensity due to a charged

conducting spherical shall at (i) a point outside the shell,(ii) A point on the surface of the shell and (iii) A point inside the shell.

46*. State and explain Coulombs law. Derive it from Gauss law.

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CURRENT ELECTRICITYLONG ANSWER QUESTIONS

7***. State and explain Kirchhoff’s law in electricity and apply them to Wheatstone bridgeto obtain its balancing condition (Mar, 2008, 2006)

8***. Explain the principle of meter bridge. Describe an experiment for the determination ofunknown resistance of a wire.

9**. Define electric current, drift velocity and mobility of charge carriers in a conductor.Derive the relation between electric current and drift velocity of charge carriers in aconductor.

10**. Explain the principle of potentiometer. Describe an experiment for the comparison ofemf’s of two cells.

11**. Describe the construction and principle of potentiometer and explain how the internalresistance of a cell is determined using potentiometer.SHORT ANSWER QUESTIONS

47***. Write short notes on thermistor.48**. Write short notes on back emf and internal resistance of a cell (May, 2009)49**. State and explain Ohm’s law. Define Ohm.

THERMO ELECTRICITYSHORT ANSWER QUESTIONS

50***. Write short notes on the working of a thermopile.51***. Explain construction and working of Dud dell’s thermo galvanometer.52***. what is seebeck effect. Explain how thermo emf varies with temperature in a

thermocouple, define neutral and invertion temperature.53***. What are Peltier and Thomson effects? Define their coefficients (March, 2009)

ELECTRO MAGNETISMLONG ANSWER QUESTIONS

12***. Obtain an expression for the torque on a loop placed in a uniform magnetic filed.Describe the construction and working of moving coil galvanometer?

(M06, 09, May, 2006, May, 2009)13***. Describe the growth and decay of current in an inductance, resistance circuit. How the

growth and decay are affected with different values of inductance discuss? (M07)14***. How is a galvanometer converted into an ammeter? Why parallel resistance is smaller

than galvanometer resistance? Explain (March, 2005)15***. Describe the growth and decay of current in resistance, capacitance circuit? Define

time constant. (March, 2007)16***. How is a galvanometer converted in to a voltmeter? Why series resistance is greater

than galvanometer resistance? Explain (March, 2005)17*. Obtain an expression for impedance and current in series LCR circuit. Deduce an

expression for the resonating frequency of an LCR series resonating circuit.SHORT ANSWER QUESTIONS

54***. State and explain Lenz’s law with examples55***. Derive an expression for a force between two parallel conductors carrying a current.

(May, 209)56***. What is a shunt? Deduce expressions for the current flowing through the galvanometer

and shunt resistance.57**. State the principle on which a transformer works. Describe the working of a transformer

with necessary theory. Mention its uses. (May, 2006)58**. State and explain Bio-Savart law.59**. Explain instantaneous, maximum, and rms values of a current.

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ATOMIC PHYSICSSHORT ANSWER QUESTIONS

60***. What is Moseley’s law? Discuss briefly its importance. (March, 2005)61***. Describe the origin of X-ray spectra. Explian continuous and characteristic x-ray

spectrum (March, 2007)62***. Define specific charge? Describe Thomson’s experiment to determine e/m of an electron

with relevant theory. (May 2006, Mar 2008)63***. What is photo electric effect? Mention the laws of photoelectric effect. Explain these

laws using Einstein’s equation of photo electric effect? (Mar 2005, 2009)64**. Give the applications of photoelectric cells.NUCLEAR PHYSICS

LONG ANSWER QUESTIONS18***. Explain the principle and working of a nuclear reactor with the help of a labeled

diagram (Mar 09)19**. Define binding energy. How does binding energy per nucleon vary with mass number?

What is it significance.SHORT ANSWER QUESTIONS

65***. What are mass defect and binding energy? How is mass defect related to bindingenergy? (March, 2006, May, 2009)

66***. Define the term ‘decay constant’ for a radioactive substance. Deduce the relationbetween decay constant and half life period. (May, 2009)

67***. Explain the source of stellar energy. Explain the carbon-nitrogen cycle and proton-proton cycle occurring in stars. (Mar 2006, 2007)

68**. Write a note on ‘Breeder reactor’.69**. Write a short note on the discovery of neutron.70* Mention the uses of radioisotopes. (Mar 2008)71*. What is nuclear fission? Explain liquid drop model of nuclear fission?*72*. Difference

between nuclear fusion and nuclear fission.

73*. State the properties of , ,α β γ ray.

SEMI CONDUCTORSLONG ANSWER QUESTIONS

20***. What is rectifier? Explain working of half wave and full wave rectifiers with diagramsMention the expression for its efficiency? (Mar 2009, 2005, 2007)

21***. Describe a transistor and explain its working. (Mar 2008)SHORT ANSWER QUESTIONS

74***. Explain the operation of NOT gate and give its truth table.75***. What is a Zener diode? Explain how it is used as voltage regulator76***. Define NAND and NOR gates. Give their truth tables.77** Discuss the behaviour of a p-n junction. How does a potential barrier develop at the

junction.78**. What is a junction diode. Explain the formation of depletion layer at the junction.

Explain the variation of depletion layer in forward and reverse biased condition.79* Draw and explain the current-voltage (I-V) characteristic curves if a junction diode in

forward and reverse bias.VERY SHORT ANSWER QUESTIONS

WAVE MOTION1. What is the phase difference between incident and reflected waves at a) an open end

and b) closed end?2. What happens to the fundamental frequency of a stretched string when its linear density

becomes1/4thof its initial value? (Mar 2006-2007)

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3. What is the ratio of the frequencies of harmonics in an air column of same length in a)a closed pipe and b) an open pipe

4. Mention any two applications of beats.5. What are “Focusing” and “Echelon effects”?6. What do you mean by reverberation time an auditorium7. What is sound absorber. Give two examples for good absorbers. (Mar 2006)8. The length of a wire vibrating with a frequency of 340 Hz is 1m . It its length is

changed to 1.6 m, find the frequency.9. Name any two musical instruments whose working depends on transverse vibrations

of a string (M 2008)10. What is reverberation? Who is the founder of architectural acoustics?

(M05, May 2006)11. What is Newton’s formula for velocity of sound in a gas? How is it corrected by

Laplace?12. What is “End correction” in resonating air column?13. What happens to the frequency of a tuning fork a) When it is loaded with a little wax

and b) When it is filed?14. What is “Absorption coefficient”? which is a better absorber of sound, glass or fibre

glass?15. What is the ratio of the frequency of fourth overtone to the fundamental frequency

of a stretched string?RAY OPTICS

16. Given the ratio of velocities of two light waves traveled in vacuum and having wavelengths 5000Ao and 6000Ao.

17. Why do diamonds sparkle?18. What is normal adjustment of a telescope? In What way it is better?19. What is the use of erecting lens in a terrestrial telescope? What is its magnification?20. What are the advantages of Rams den’s eyepiece?21. What are the demerits of Huygens’ eyepiece?22. The angles of deviations for violet and red colors of a crown prism are 5.23o and 5.15o

respectively. Find the dispersive power of the prism? (Mar 2005)23. The measurements taken in Ramdesns eyepiece more worthy (reliable) than Huygens

eyepiece. Why? (Mar 2006)24. Define critical angle. Mention its relationship with refractive index. (M07, May 2006)25. If the refractive index of a medium is 1.5, find the critical angle.26. Write the difference between microscope and telescope. (May 2009)27. Mention the types of chromatic aberration (Mar 2008)28. What are Fraunhoffer lines? Explain their origin.29. State and explain Huygens’ principle.30. State the consequences of total internal reflection.31. What is an optical fiber? State its principle.32. Can we minimize spherical and chromatic aberrations simultaneously? If so, how?

PHYSICAL OPTICS33. How does the spacing between fringes in Young’s double slit experiment change. a) if

the slit separation is increased? b) If the colour of the light is changed from red toblue?

34. If Young’ two slit interference experiment is done with white light what would beobserved?

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35. If a polarizer is placed in front of each slit, what changes be observed in the interferencefringes. A) When the two polarizing axes are parallel b) when the two polarizing axesare perpendicular?

36. What are half period zones? What is their other name? (Mar 2007)37. Distinguish between geometric and physical (wave) approximations of light.38. How does the spacing between fringes in Young’s double slit experiment change. a) if

the slit separation is increased? B) if the colour of the light is changed from red toblue?

39. What change will occur in a Young’s double slit experiment if the whole apparatus isimmersed in water rather than air?

MAGNETISM40. Define the magnetic moment of a bar magnet. What is its direction?41. Do you find two magnetic field lines intersecting? Why?42. The force between two magnetic poles separated by a distance‘d’ in air is ‘F’. At

what distance between them the force becomes doubled?43. What is the magnetic moment of a semi circular magnet of radius ‘r’ and pole strength

‘m’44. In the equal distance method of a deflection magnetometer, the deflections produced

by two bar magnets are 300 and 600. What is the ratio of their magnetic moments?(M07)

45. Why magnetic poles are reversed at a given position on a deflection magnetometer totake readings? (March, 2005)

46. The magnetic moment of the magnet is 30 A-m2. Its length 10cm. What is its polestrength (M 2006 )

47. State inverse square law in magnetism and mention the mathematical expression.(March, 2008)

48. Where do you find the null points in the combined field due to a bar magnet and theearth, when i) the N-pole of the magnet is kept towards the north of the earth, ii) theS-pole of the magnet is kept towards the north of the earth

ELECTRO STATICS49. What is meant by the statement ‘charge is quantized’?50. The electric lines of force do not intersect. Why?

51. Three capacitors of capacitance

4 Fµ

,

6 Fµ

and

8 Fµ

are connected in parallel

a) What is the ratio of charges? b) What is the ratio of potential difference?52. Can there be electric potential at a point with zero electric intensity?53. The potential of earth is taken as zero. Explain (March, 2006)54. What is the difference between electric lines of force and magnetic lines of induction?

(March, 2008)55. State Gauss’s law in electrostatics

56. Three condensers of

1 fµ

,

2 fµ

and

3 fµ

are connected in series. What is the ratio of

their potential differences? (March, 2007)

57. The potential at the origin is zero, due to electric field

ˆ ˆE 20i 30j N / c= +

. Find the

potential at point ( )P 2m, 2m .

58. 1C of charge is equal to the charge of n number of electrons in magnitude. What isthe value of n?

59. What happens to the force between two charges if the distance between them is a)halved b) doubled?

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60. A charge q of mass m starting from rest is allowed to move between two plates havinga potential difference of V volt. What is the final velocity of it?

61. Repulsion is the sure test of electrification than attraction. Why?62. Write down the uses of capacitors?

CURRENT ELECTRICITY63. What are ohmic and non ohmic devices? Give examples64. The manganin wire is used in the preparation of standard resistances. Why?65. How many electrons flow through a wire when 1A current passes for 1 millisecond?

(May 2006)66. Write two differences between emf and p.d. (Mar 2005)67. Which of two, namely voltmeter and potentiometer is preferable to measure the emf

of a batter? Why?68. When is the series combination of cells advantageous and why? (Mar 2006)69. When is the parallel combination of cells advantageous and why? (Mar 2009)70. What is internal resistance of a cell? Write the value of internal resistance of an ideal cell.

(May 2009)71. What is the specific resistance of material of a conductor. Mention its units. (M05)

THERMO ELECTRICITY72. What are thermoelectric refrigerators?

ELECTRO MAGNETISM73. What is the force on a conductor of length l carrying current ’i’ when it is situated

in a magnetic field of induction B? When is it maximum? (Mar 2007)74. State Fleming’s left hand rule.75. Define coefficient of self induction, coefficient of mutual induction.76. What type of transformer is used in a bed lamp.77. What is transformer ratio?

78. A current of 2A is passed through a coil of 1000 turns to produce a flux of 0.5 wbµ .

Calculate the self inductance of the coil (Mar 2008)79. The current in a coil changes of 5A to 10A in 10-2 s. Then an emf of 50 mill volts is

induced in a coil neat it. Calculate the mutual inductance of the coil (Mar 2009)80. A coil of area 100 cm2 having 500 turns carries a current of 1mA. It is suspended in a

uniform magnetic field of induction 10-3 Wbm-2. Its plane makes an angle of 600 withthe lines of induction. Find the torque acting on the coil.

81. A step-up transformer works on 220V and gives 2A to an external resistor. The turnratio between the primary and secondary coils is 2 : 25.Assuming 100% efficiency,find the secondary voltage. Primary current and power delivered.

ATOMIC PHYSICS82. What is work function of a metal (March, 2006)83. What is Compton effect?84. If a proton and an electron have same de Broglie wavelength, which has more

momentum and kinetic energy? (March, 2008)85. Is photon a wave or a particle? What is its rest mass?86. Can X-ray produce photoelectric effect? Calculate the work function of a metal

production photo electrons with X-rays of wavelength 1Ao

87. What is the equation of wavelength associated with a moving particle?NUCLEAR PHYSICS

88. Give two important characteristics of nuclear forces?89. Neutrons are the best projectiles of produce nuclear reactions. Why?90. State any two properties of neutron. (March, 2008)

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91. What is thermal neutron? What is its importance?92. What is annihilation of matter? Given an example93. What are isotopes and isobars94. What will be the ratio of the radii of two nuclei of mass numbers A

1 and A

2

SEMI CONDUCTORS95. What are the majority and minority charge carriers in a p-type semi conductor? (M08)96. How is a battery connected to a junction diode in 1) forward and 2) reverse-bias?97. Which gates are called universal gates?98. Draw the circuit symbols of p-n-p and n-p-n transistor.

COMMUNICATION SYSTEMS99. What are the basic blocks of communication system?100. What is sky wave propagation?101. Define modulation. Why is it necessary? (March, 2009)102. What is “World Wide Web” (WWW)?103. Mention the frequency range of speech signals.

PROBLEMSTHREE STAR QUESTIONS

WAVE MOTION1. Two sound waves of lengths 9 and 10 meters produce 34 beats in 9 seconds. Find

the velocity of sound.2. Two tuning forks give 4 beats per second when sounded simultaneously. The frequency

of one of the forks is 384 Hz. When the other fork is loaded with a little wax 6 beatsper second are produced. What is the frequency of the second fork?

3. The frequency of a tuning fork A is 2% greater than that of a standard fork K. Thefrequency of another tuning fork B is 3% less than K. When Aand B are vibratedtogether 6 beats per second are heard per second. Find the frequencies of A and B.

(March, 2008)4. Man standing between two parallel cliffs fires a gun. He hears the first echo after 2

seconds and the next after 5 seconds. What is the distance between the cliffs? Velocityof sound in air is 350ms-1

5. A motor car approaching a cliff with velocity 108 kmph sounds horn and the echo isheard after 0.3 sec. Assuming the velocity of sound in air to be 332 ms-1. Calculate thedistance between the car and the cliff when the horn is blown. (March, 2005)

6. A string vibrates with frequency 200Hz. Its length is increased to 4/3 times the initiallength and tension is adjusted till the string vibrates with frequency 300 Hz. What isthe ratio of the new tension to the original tension? (March, 2005)

7. The inner dimensions of a rectangular room are 20 x 15 x 10m3. The average absorptioncoefficient of its surface is 0.01. Find the time of reverberation. (March, 2007)

8. Find the velocity of propagation of a transverse wave, if a string of length 0.5 mproduces a fundamental note of frequency 300Hz.

9. The frequency of the fundamental note of a tube closed at one end is 200Hz. Whatwill be the frequency of the fundamental note of a similar tube of same length butopen at both ends (May, 2009)

10. Progressive transverse wave is given by the equation

( )10

y 0.01sin x 330t3

π= +

. Find its

(i) amplitude (ii) frequency (iii) velocity and (iv) wave length.11. Two wires are fixed on a sonometer wire. Their tensions are in the ratio 8: 1, the

lengths in the ratio 36 : 35, the diameters in the ratio 4 :1 and densities in the ratio 1: 2.If the string of higher pitch has a frequency of 360 Hz calculate the frequency of theother string.

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12. A rectangular class room of volume 20 x 15 x 10m3 has a surface whose averageabsorption coefficient is 0.035 metric Sabine. Calculate the time of reverberation ofthe room. When a material of area 1500 m2 is brought into the room, the reverberationtime falls to 2.5 seconds. Calculate the absorption coefficient of the material?

RAY OPTICS13. A prism of refracting angle 4o is made of material of refractive index 1.652. Find its

angle of minimum deviation.14. Find the critical angle of a denser medium of refractive index 1.65 for its interface with

air.15. The focal length of a converging lens is 8cm. Find its magnifying power when it is

used as a reading lens to form the image at near point.16. The refractive indices of flint glass prism for C,D and F lines are 1.790 , 1.795 and

1.805 respectively. Find the dispersive power of the flint glass prism.17. The refractive index of the material of a plane concave lens is 10/6. Find its focal

length in air and in water as its radius of curvature is 0.3m. The refractive index ofwater with respect to air is 4/3. (March, 2006)

PHYSICAL OPTICS18. An un polarized light of intensity I

0 is transmitted by a polarizer and then by the

second one. The angle θ between the special directions (transmission directions) is300 . What is the intensity of the light received by the observer from the secondpolarizer?

MAGNETISM19. A bar magnet of magnetic moment M is bent into a semicircle. What is its new

magnetic moment?20. A bar magnet of length 10cm and pole strength 2Am is making an angle 60o with a

uniform magnetic field of induction 50 Tesla. Find the couple acting on it.21. Two short bar magnets having magnetic moments in the ratio 27:8 are placed on

opposite sides of a deflection magnetometer. Find the distance of stronger magnet ifthe weaker magnet is at a distance of 10cm from the centre of the magnetometer fornull deflection.

22. A bar magnet of moment of inertia 1 x 10 -2 kg m2 vibrates in a magnetic field ofinduction 0.36 x 10-4 Tesla. The time period of vibration is 10s. Find the magneticmoment of the bar magnet. (March, 2007)

ELECTRO STATICS23. Three charges +q, -q and –q are kept at the vertices of an equilateral triangle of 10cm

side. Calculate the potential at the mid point in between –q, -q, if q =

5 cµ

.

24. Two positive changes

12 Cµ

and

10 Cµ

, are initially separated by 10cm. Calculate the

work done in bringing the two charges 4cm closer.

25. Four charges

1q 0.02 Cµ= −

, 2q 0.04 Cµ= , 3q 0.02 Cµ= and

4q 0.04 Cµ= − are at the four

corners of a square of side 9cm. Calculate the potential at the centre of the square.26. The plates of a parallel plate capacitor are separated by 0.1mm. What should be the

plate area to have a capacitance of 2pF? (take 12 2 1 2

o 8.85 10 C N mε − − −= × )

27. Two point charges of magnitude 6 cµ ,

8 cµ

are separated by a certain distance in air the

force between them is 27N. Find the force between them if a) the distance betweenthem is increased by 3 times b) the distance between them is decreased by 3 times.

CURRENT ELECTRICITY28. Find the balance length in a meter bridge, if the resistance in the left and right gaps is in

the ratio of 2: 3. (March, 2007)

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29. A wire of resistance 10 ohm is elongated by 10%. Find the resistance of the elongatedwire. (hint: when the same wire is elongated, the volume of the wire remains constant )

THERMO ELECTRICITY30. The neutral temperature of a thermocouple is 180oC. What is the temperature of

inversion when the cold junction at 20oC? (Mar 2008, 2007)31. The temperature of inversion of iron- copper thermocouple is 590oC and cold junction

temperature is 0oC. What is the neutral temperature?ELECTRO MAGNETISM

32. A long straight conductor carrying a current of 2A is in parallel to another conductorof length 5cm and carrying a current 3A. They are separated by a distance of 10cm..Calculate a) B due to first conductor at second conductor b) The force on the shortconductor

33. A coil of area 100 cm2 having 500 turns carries a current of 1mA. It is suspended in auniform magnetic field of induction 10-3 Wbm-2. Its plane makes an angle of 60o withthe lines of induction. Find the torque acting on the coil.

34. The resistance of galvanometer is

999Ω

. A shunt of

1Ω

is connected to it. If the maincurrent is 10-2A, what is the current flowing through the galvanometer?

35. A wire of 10cm length is placed in a uniform magnetic field of induction 0.02T making,an angle of 30o with it. If 5A of current flows through it calculate force acting on it

(M06)36. Two unknown resistances P and Q are connected in left and right gaps of a meter

bridge and balancing point is obtained at 60cm from the left. When a

20Ω

resistanceis connected in parallel to P the balance point is at 50cm . Calculate P and Q

(May, 2009)ATOMIC PHYSICS

37. Work function of a metal is 3.0eV. It is illuminated by a light of wavelength 3 x 10-7 m.Calculate the maximum energy of the electron.

38. Find the momentum of an electron having wavelength 2A ( h = 6.62 x 10-34 Js) (M06)

NUCLEAR PHYSICS

39. Find the binding energy of

56

26 Fe

. Atomic mass of Fe is 55.9349 u and that of hydrogen

is 1.000783 u. Mass of neutron is 1.00876 u.

SEMI CONDUCTORS

40. In a transistor circuit the base current changes from 50 Aµ to

150 Aµ

. The corresponding

change in the collector current is from 0.2mA to 4.2 mA. Find the current gain.

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Sr Physics - Chapter Wise Important Questions