Physics One Mark Old

8/3/2019 Physics One Mark Old

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KAMARAJ SPECIAL SCHOOL, CHIDAMBARAM

Std : XII Physics Lesson X (One mark questions)

1. High frequency waves follow

a. ground wave propagation b. line of light direction c. Ionosphere propagation d. the curvature of earth

2. The main purpose of modulation is to

a. combine two waves of different frequencies b. acquire wave shaping of career wave

c. transmit low frequency wave over long distance efficiently d. to produce side bands

3. In amplitude modulation

a. the amplitude of the career wave varies in accordance with the amplitude of modulating signal.

b. amplitude of the career wave varies in accordance with the frequency of the modulating signal.c. modulating frequency lies in the audio range.

4. In amplitude modulation, the band width is

a. equal to the signal frequency b. twice the signal frequency

c. thrice the signal frequency d. four times the signal frequency

5. In phase modulation

a. only the phase of the career wave varies b. only the frequency of the career wave varies.

c. both the phase and frequency of the career wave varies d. there is no change in the frequency

6. The R.F. channel in a radio transmission produces

a. audio signals b. high frequency career waves

c. both audio signal and high frequency radio wave d. low frequency career wave

7. The purpose of dividing each frame into two fields so as to transmit 50 views of the picture per second is,

a. to avoid flicker in the picture b. the fact tat handling of higher frequencies is easier

c. that 50 HX is power line frequency in India d. to avoid unwanted noises by the signal8. Printed documents to be transmitted by fax are converted into electrical signals by the process of

a. refraction b. scanning c. modulation d. light variation

9. Communication refers to

a. sending information b. receiving the information

c. processing the information d. sending receiving and processing the information

10. Ground wave propogation takes place

a. when the transmitting antenna is close to the earth b. receiving antenna is close to the earth

c. when the transmitting and receiving antennas are far off from earth

d. when the transmitting and receiving antennas are close to the earth

11. Ground wave propogation is of prime importance

a. short wave signals only b. long wave signals only

c. medium wave signals only d. medium and long wave signals12. Space wave propogation is particularly suitable for the frequency

a. above 40 MHZ b. below 30 MHZ c. below 20 MHZ d. above 30 MHZ

13. Mechanism involved in sky wave propogation is

a. reflection b. refraction c. interference d. polarisation

14. Long distance radio communication is possible though the

a. ground wave propogation b. surface wave propogation c. the sky wave propogation d. all the above

15. The refraction index of the varies layers of ionosphere varies with respect to

a. electron density only b. frequency of the incident wave only

c. electron density and frequency of incident wave d. intensity of the incident wave only

16. Ionosphere consists of

a. electrons only b. positive ions only c. negative ions only c. all the above

17. As the ionization density increases while a wave approaches a layer, the refractive index

a. increases b. decreases c. remains constant d. becomes equal to 118. The part of atmosphere up to 15 km from earth is called

a. stratosphere b. troposphere c. ionosphere d. chromosphere

19. Music, speech etc are converted into audiosignals using

a. level speaker b. photo cell c. diode d. microphone

20. Electrical signals are converted sound using

a. diode b. microsphere c. loudspeaker d. photocells

21. Audio frequency range is

a. 20 to 200000 HZ b. 20 to 20000HZ c. 20 to 2000000HZ d. 20 to 2000HZ

22. Human voice and music contain waves with frequency range of

a. 3 to 30 HZ b. 30 to 300 HZ c. 3000 to 30000HZ d. 300 to 3000HZ

23. The radiation of electrical energy is practicable only at

a. low frequency b. very low frequency c. microwave frequency d. high frequency

24. Which signals can be sent through thousands of kilometers with comparatively small power

a. audio signals b. video signals c. high frequency signals d. low frequency signals

25. In amplitude modulation, which is changed according to intensity of signal

a. frequency of career wave b. phase of the career wave

c. both frequency and phase of career wave d. amplitude of career wave

26. The factor that determines the strength of quality of the transmitted signal is

a. in factor b. frequency of career wave c. frequency of modulating d. modulation factor

27. For effective modulation, the degree of modulation should

a. exceed 100% b. exceed 200% c. never exceed 50 % d. never exceed 100%

28. The magnitude of amplitude of both upper and lower side band is

a. 2 times career amplitude b. of career amplitude c.2

mtimes career amplitude d.

2

mtimes

career29. If the modulation factor is unity, the magnifier of amplitude of upper and lower side band

a. twice the career amplitude b. half the career amplitude


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c. 2 times career amplitude d.2

1times career amplitude

30. Which modulation facilitates highest transmission speed on a given bandwidth

a. amplitude modulation b. frequency modulation c. phase modulation d. all the above

31. For the propose of coupling the transmitter and receiver to the space link, we use,

a. amplifier b. oscillator c. antenna d. FAX

32. Transmitting antenna converts the

a. electrical signal into electrical energy b. electrical signal into magnetic energy

c. electrical signal into electromagnetic energy d. electromagnetic energy into electrical signals

33. Receiving antenna converts thea. electrical signal into electromagnetic b. electrical signal into electrical energy

c. electrical signal into magnetic energy d. electromagnetic energy into electrical singal

34. The ability to amplify the weak signal is known as

a. sensitivity b. selectivity c. fidelity d. compatibility

35. The intermediate frequency used in radio receiver is

a. 10.7 MHZ b. 455 KHZ c. 475 KHZ d. 455 HZ

36. For super hetrodyne FM receiver the intermediate frequency is

a. 455 HZ b. 455 KHZ c. 10.7 MHZ d. 45 KHZ

37. For commercial FM broadcast the frequency deviation sound signal is

a. 25 KHZ b. 50 KHZ c. 75 KHZ d. 100 KHZ

38. In T.V. transmission sound signals are

a. amplitude modulated b. frequency modulated c. phase modulated d. none of the above39. T.V. transmission picture signals are

a. amplitude modulated b. frequency modulated c. phase modulated d. none of the above

40. Vidicon camera tube works on

a. photoconductivity b. thermoelectric effect c. thermionic emission d. seeback effect

41. When exposed to light the resistivity of the photo conducting material

a. decreases b. increases c. increases or decreases d. is not altered

42. In vidicon camera tube the front face of the camera tube is coated with

a. antimony disulphide b. aluminium oxide c. zinc sulphide d. trioxide

43. In vidicon camera to be, on the back side of the target plate is coated with photo sensitive material

a. antimony trifluoride b. zinc sulphide c. tin oxide d. aluminium oxide

44. The frequency of scanning is

a. 20 per second b. 25 per second c. 50 per second d. 100 per second

45. How many synchronizing pulses are used for scanning?a. one b. two c. three d. four

46. In 625 live system, the horizontal frequency of scanning is

a. 625 HZ b. 525 HZ c. 50 HZ d. 15625 HZ

47. In 625 line system, the time taken to scan one horizontal line is

a. 6.4 s b. 64 s c. 0.064 s d. 0.64 s48. In interlaced scanning the vertical scanning frequency is

a. 10 fields / sec b. 25 fields per second c. 50 fields / sec d. 100 fields per second

49. In CCIR standard the channel with for T.V transmission is

a. 3.5 MHZ b. 38.9 MHZ c. 33.4 MHZ d. 7 MHZ

50. A modem is used for

a. modulation only b. demodulation only c. modulation and demodulation d. printing the information

51. In T.V. transmission, the picture should not be scanned

a. vertical scanning pulse b. horizontal scanning pulse c. blanking pulse d. triggering pulse

52 Optical fiber works on the principal of

a. total internal reflection b. refraction c. reflection d. polarization

53. Satellite orbiting the earth will be at a height of

a. 36000 km b. 3600 km from earth c. 360 km from earth d. 36 km from earth

54. For uplink transmission commercial communication satellites are,

a. 5 MHZ band with near 6 GHZ b. 50 MHZ band with near 6 GHZ

c. 500 MHZ band with near 6 GHZ d. 500 MHZ band with near 6 GHZ

55. In downlink transmission commercial communication satellites are,

a. 500 MHZ band with near 4 GHZ b. 50 MHZ band with near 4 GHZ

c. 500 MHZ band with near 5 MHZ d. 5 MHZ band with near 4 GHZ

56. In actual practice the band with used for uplink transmission by the satellite

a. 5.725 to 0.075 GHZ b. 3.4 to 4.8 GHZ c. 6.725 to 7.075 GHZ d. 5.725 to 6.075 GHZ57. In actual practice the band with used for downlink transmission by satellite

a. 5.725 to 7.075 GHZ b. 3.4 to 4.8 GHZ c. 6.725 to 7.075 GHZ d. 5.725 to 6.075 GHZ

58. To avoid interference the downlink frequency should be away from uplink frequency by an interval

a. 2 GHZ b. 3 GHZ c. 4 GHZ d. 5 GHZ

59. The gain of the amplifier the mid frequency region is 200. The gain of the amplifier at lever cut off frequency is

a. 20 b. 100 c. 141.4 d. 282.2

60. If 900 KHZ station is tuned then the local oscillation will have to produce then a frequency of

a. 600 KHZ b. 455 KHZ c. 10.7 KHZ d. 1355 KHZ

61. A carrier of 5 KHZ sinusoidal wave of amplitude 10mv is modulated by a 5 KHZ sinusoidal audio signal wave of amplitude

6mv find the upper and lover side band

a. 4.995 and 5.005 MHZ b. 9.995 MHZ to 10.005 MHZ c. 4.5 MHZ to 5.5 MHZ d. 10 MHZ to 15 MHZ

62. A carrier wave of amplitude 10 mv is modulated by a sinusoidal audio singal wave of amplitude 6 mv. The modulation

factor isa. 0.6 b. 6 c. 60 d. 0.06


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Std : XII Physics Lesson IX (One mark questions)

1. Electrons in the atom of an element which determine the chemical and electrical properties are called

a) Valence electrons b) Revolving electrons c) Excess electrons d) Active electrons

2. In an N - Type semiconductor, there are

a) Immobile negative ions b) No minority carriers c) Immobile positive ions d) Holes are majority carriers.

3. In a P-Type semiconductor, there are

a) Immobile negative ions b) No minority carriers c) Immobile positive ions d) Electrons are majority carriers

4. The reverse saturation current in a P-N junction diode is only due to

a) majority carriers b)minority carriers ) acceptor ions d)donar ions5. In P- Type semiconductor,

a) electrons are majority carriers b)holes are majority c arriers

c)holes are minority carriers d)immobile positive ions are majority carriers.

6. In N- Type semiconductor ,

a) electrons are majority current carriers b) holes are majority current carriersc) immobile negative ions d) electrons are minority carriers

7. In the forward bias characteristic curve a diode appears as

a) A high resistance b) a capacitor c)an OFF switch d)an ON switch

8. Zener breakdown is primarily due to

a) collision b) ionization c)breaking of bonds in high electric field d) none by the above

9. Avalanche breakdown is primarily dependent on

a) collision b) ionosation c)doping d)recombination10. The colour of light emmited by LED depends on

a) the reverse bias b)the amount of forward current c) The forward bias d) type of semi-conductor material

11. The emmiter-base junction is forward biased, the collector-base junction is reverse biased. If the base current is

increased, then its

a) VCE will increase b) Ic will decrease c)Ic will increase d) Vcc will decrease

12. Improper biassing of a transistor circuit produces

a) heavy leakage of emitter current b)distorsion in the output signalc)excessive heal at collector terminal d) faulty location of load line

13. An oscillation is

a) an amplifier with feedback b) a convertor of AC into Dc energy

c) nothing but an amplifier d)an amplifier without feed back

14. In a colpit oscillator circuita) Caparitance feed back is used b) tapped coil is used

c) no turned LC circuit is used d) no capacitor is used

15. Since the input impedance of an ideal operational amplifier is infinite

a) Input current is zero b) the output resistance is high

c) the output voltage becomes independent of load resistance d) it becomes a current controlled device

16. The following arrangement performs the logic function of

a) AND b) OR c) NAND d)EX-OR

17. The output Y of the following circuit is 1, if ABC must be

a)0 1 0 b)1 0 0 c)1 0 1 d) 10 0

18. According to the law of Boolean algebra (A+Ab) is equal to

a)A b)AB c)B d)A

19. The Boolean expression ABC can be simplified toa) AB + c b) A . B . C c) AB + BC + CA d. A + B + C

20. A solid state device mainly consists of a

a) conducting material b) insulating material c) semiconducting material d)super conducting material

21. Resistively of a semiconductor

a) greater than that of conducting material b) less than that of conducting material

c) similar to that of insulator d) equal to that of conductor

22. Of the following which is wrong?

a. Resistively of semi conductors is approximating 10-2 to 104 ohm - meter

b. Resistance of semi conducting devices decreases with increase of temperature

c. Resistance of a conductor increases with increases of temperature

d. Resistively of a conductor lies between 102 to 104 ohm meter.

23. The resistively of a conductor isa. 10-6 to 10-8 ohm meter b. 10-2 to 104 ohm meter c. 108 to 1014 ohm meter d. 10-8 to 10-14 ohm meter

24. Resistively of an insulator lies between

a. 10-2 to 104 ohm meter b. 10-6 to 10-8 ohm meter c. 108 to 1014 ohm meter d. 10-8 to 10-14 ohm meter25. Resistively of a semi conductor lies between

a. 10-2 to 104 ohm meter b. 108 to 1014 ohm meter c. 10-6 to 10-8 ohm meter d. 10-8 to 10-14 ohm meter

26. An example of semi conductor is

a. Fe b. Co c. Ni d. Ge


a. Fe b. Ni c. Cu d. In


a. Ni b. Ge c. Si d. both b and c

29. For an insulator the energy gap isa. less than 3ev b. less than 0.7 ev c. more than 3ev d. 0.7ev

30. For a semi conductor germanium, the energy gap is

a. 1.1 ev b. 0.7 ev c. 3 ev d. above 3 ev


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31. For Si the forbidden energy gap is

a. 0.7 ev b. 1.1 ev c. 3 ev d. more than 3 ev

32. For conductors the energy gap is

a. 0.7 ev b. 1.1 ev c. more than 3 ev d. no energy gap

33. In glass the forbidden energy gap is of the order of

a. 3 ev b. 6 ev c. 10 ev d. 0.7 ev

34. Electrons in an intrinsic semi conductor which more into conduction bond at high temperatures are called

a. valence electrons b. hole c. donor d. intrinsic carrier

35. In intrinsic semi conductors

a. number of free electrons is equal to number of holes b. no. of free electrons is more than the number of holesc. number of free electrons is less then the number of holes d. number of free electrons is zero

36. Amount of imparity atoms to be added to an intrinsic semi conductor is of the order of

a. 50ppm b. 100 ppm c. 500 ppm d. 1000 ppm

37. Donor atom is a

a. trivalent b. tetravalent c. pentavalent d. divalent38. Acceptor atom is a

a. trivalent b. tetravalent c. pentavalent d. divalent

39. Of the following donor atoms are

a. Si and Ge b. Aluminium and gallium c. Bismuth and arsenic d. boron and Indium

40. Of the following accepter atoms are

a. Si and Ge b. Aluminium and gallium c. Bismuth and arsenic d. Boron and Aluminium

41. The follering is an example of acceptor atoma. Al b. Bi c. P d. As

42. The difference of potential from are side of the barrier to the other side of a PN junction diode is known as,

a. depletion region b. potential gradient c. potential barrier d. contact

43. The potential barrier in a PN javention dilate deports on

a. Of electrons b. number of holes c. potential difference d. nature of the material

44. In forward biased P-N junction diode

a. potential barrier is reduced b. potential barrier is increasedc. Width of the potential barrier is increased d. potential barrier remains the same

45. Rectifier efficiency of a half wave rectifier is

a. 60.4% b. 81.2% c. 40.6% d. 30.2%

46. Rectifier efficiency of a full wave rectifier is

a. 60.4% b. 81.2% c. 40.6% d. 30.2%47. Variation of d.c. output voltage as a function of d.c. load current is called

a. rectification b. filter c. regulation d. full wave rectification

48. Percentage of regulation is known as,

a. 100XV

VV

noloade

loadnoload b.

100

loadnoload VV c. 100XV

VV

loade

loadnoload d. 100X

V

VV

loade

noloadload

49. Zener diodes are used as

a. rectifiers b. filters c. regulators d. amplifiers

50. Sever current is

a. dependent on applied voltage b. independent of applied voltage

c. dependent on the material of the diode d. dependent on knee voltage

51. A reverse biased heavily doped semi conductor PN junction diode isa. LED b. LCD c. zener diode d. transistor

52. A diode working in what region can act as a voltage regulator

a. normal b. saturated c. break down d. constant voltage

53. The reverse saturation current in a PN junction diode is only due to

a. majority carriers b. Minority carriers c. acceptor ions d. denar ions

54. A forward biased diode will act as

a. a high resistance device b. a capacitor c. an off switch d. an ON switch

55. During the normal operation of a transistor, if base current is increased then its

a. VCE will increase b. IC will increase c. IC will decrease d. VCC will increase

56. The mani feaction of the emitter is to supply,a. electrons b. majority current carriers c. holes d. minority current carriers

57. In any transistor, which of the following is true

a.C

BE

I

II = b. IC = IE + IB c. IE = IB + IC d.

B

EC

I

II =

58. Ratio of collection current to emitter current is

a. b. c. A d. A

59. Value of in terms of is given by

a. =

+1b. =

1c. =

+1d. =

1

60. The value of in terms of is

a. =

1b. =

+1c. =

+1d. =

1

61. The value of in any transistor lies betweena. 50 to 300 b. up to 1000 c. 0 to 9 d. 0.95 to 0.99

62. The value of in a transistor lies between

a. 50 to 300 b. 0.95 to 0.99 c. 0 to 9 d. 0 to 50


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63. The value of

B

BE

I

Vis called

a. input impedance b. output impedance c. current gain d. current gain

64. Common emitter configuration has

a. high input impedance b. high current gain c. high voltage gain d. all the above

65. In CE amplifiers the phase reversal between input and output voltages is

a. 0o b. 90o c. 180o d. 270o

66. The most widely used method of providing bias and stabilization of transistor

a. base bias b. base bias with emitter feed backc. base bias with collector feed back d. voltage divider bias

67. Voltage gain of R.C coupled amplifiers depends on

a. Current range b. voltage range c. frequency range d. phase range

68. The voltage gain of the amplifiers is constant at,

a. low frequency range b. high frequency rangec. both low and high frequency range d. mid frequency range

69. At lower and upper cut off frequency the gain of the amplifier is

a. two times mid frequency gain b. 2 times mid frequency gain

c.2

1times mid frequency gain d.

2

1times mid frequency gain

70. When a number of amplifiers are cascaded the over all voltage gain is equal toa. sum of the voltage gain b. difference of voltage gain c. product of voltage gain d. mean of voltage gain

71. When a fraction of of output voltage is fed into the input, the new input voltage will be

a. oii VVV +=1

b. oii VVV =1

c. oii VVV =1

d. oii VVV 21 +=

72. Voltage gain of the amplifier with positive feed back

a.A

A

+1b.

A

A

1c.

A

A1d.

A

A+1

73. Essential condition for the maintenance of oscillation

a. =A

1with positive feed back b. =

A

1with negative feed back

c. = 1 with positive feed back d. = A with negative feed back

74. The value of

B

BE

IV is called

a. input impedance b. output impedance c. input admittance d. output admittance

75. Frequency of oscillation of a colpilies oscillator is

a. f =( )CMLL 22

1

21 ++b. f =

212

1

CCc. f =

21

21

2

1

CC

CC

+d. f =

LCC

CC

)(2

1

21

21+

76. Operational amplifier consists of

a. 20 transistors, 11 resistors and 1 capacitor b. 20 resistors and 11 transistor and 1 capacitor

c. 20 capacitors, 11 resistors and 1 transistor d. 20 transistor, 11 capacitors and one resistor

77. In C B connection =0.95, IE = 1 mA, then collector current is

a. 0.05 mA b. 0.95 mA c. 1.05 mA d. 0.1 mA

78. In a transistor, = 0.99, is

a. 49 b. 90 ` c. 99 d. 9.9

79. In a transistor, = 40, AT 25= collector current is

a. 100A b. 1000A c. 1mA d. 0.1 mA

80. In a transistor in C B mode IC = 12.5mA, IE = 13 mA, then T is

a. 25.5 mA b. 0.5 mA c. 50 mA d. 50A81. The input impedance of a transistor is 1000 ohms and = 100 then VBE required for collector of 1 mA

a. 1 V b. 199 mV c. 10mV d. 1 mV

82. In CE configuration IC changes from 2 mA to 4mA, When VCE is increased from 5 to 10v then the output impedance is

a. 1 kito ohm b. 1.5 ohm c. 2.0k ohm d. 2.5k ohm

83. Three amplifiers have gains 10, 50 and 80 respectively. When they are connected in cascades the overall gain is

a. 4000 b. 400 c. 40000 d. 140

84. The inductor of inductance2

4

1

H and as capacitor 4 Df are in parallel to form LC circuit then frequency of

oscillation

a. 5mH b. 0.5 MHZ c. 50MHZ d. 500MHZ

85. Find voltage at point B

a. 1.7v b. 2.0v c. 2.9v d. 3.7v


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Std : XII Physics Lesson I (One mark questions)

1. A glass rod with silk acquires a charge of +8 x 10-12C. The number of electrons, it has gained or lost is

a. 5 x 10-7 gained b. 5 x 107 lost c. 2 x 10-8 lost d. -8 x 10-12 lost

2. The electrostatic force between two point charges kept at a distance d apart in a medium r = 6 is 0.3N. The force

between them for the same separation in vacuum is

a. 20N b. 0.5N c. 1.8N d. 2 N

3. Electric field intensity is 400 Vm-1 at a distance of 2m from a point charge. It will be 100 Vm-1 at a distance of

a. 30 cms b. 4 cm c. 4 m d. 1.5 m4. Two point charges +4q and +q are placed at 30cms apart. At what print on the line joining them the electric field is

zero?

a. 15 cms from charge q b. 7.5 cms from charge q c. 20 cms from the charge 4q d. 5 cms from charge q

5. A dipole is placed in a uniform electric field with its axis parallel to the field. It experiences.

a. only a net force b. only a torque c. both a net force and torque d. neither a net force nor a torque

6. If a point lies at a distance x from the mid print of a dipole, the electric potential at that point is proportional to

a.2

1

xb.

x

1c.

3

1

xd.

2

3

1

x7. Four charges +q, +q, -q and q are placed at the corners of A, B, C and D of a square of side a. The electric potential

at the centre of the square is

a. at

q

04 b. at

q

04

2

c. at

q

04

4

d. zero

8. The electric potential energy U of two point charges is,

a. 20

21

4 rt

qq

b.

rt

qq

0

21

4c. PE cos d. PE sin

9. The work done in moving 500C charge between two points on an equipotent surface is,a. zero b. finite positive c. finite negative d. infinite

10. Which of the following quantities is a scular

a. dipole moment b. electric force c. electric field d. electric potential

11. The electric field outside the plates of two oppositely charged plane sheets of charge dencity is

a.ot2

+b.

ot2

c.

ot

d. zero

12. The unit of permi9ttivity is

a. C2N-1m-2 b. Nm2C-2 c. Hm-1 d. Nc-1m-2

13. The number of electric lines of force originating from a charge 1 C is

a. 1.129 x 1011 b. 1.6 x 10-19 c. 0.25 x 1018 d. 8.8 x 1012

14. The capacitance of a parallel plate capacitor increases from 5f to 60f when a diabetic constant of the dielectricsis

a. 65 b. 55 c. 12 d. 10

15. A hollow metal ball carrying an electric charge produces no electric field at pointsa. outside the sphere b. on its surface c. inside the sphere d. at a distance more than twice the radius

16. If two charged bodies of charges +2q and -5q are brought in contact the total charge of the system is

a. +3q b. -3q c. zero d. either +2q or -5q

17. Unit of electric field intensitya. NC-1 b. NC-1 m-2 c. Cm d. volt

18. The unit of electric charge is

a. coulomb b. ampere second c.ohm

ondvolt secd. all the above

19. Which one of the following is an insulator?

a. human body b. earth c. copper d. ebonite

20. Electrical dipolemonent always acts from

a. q to q b. +q to q c. to +q d. to q

21. A device to store charges isa. resistor b. conductor c. inductor d. capacitor

22. When a dipole is aligned with axis parallel to the field then the potential energy is given by

a. PE sin b. zero c. PE d. PE cos

23. Work done in moving a charge in an equipotent surface is

a. zero b. minimum c. maximum d. infinity

24. Which of the following is not a polar molecule?

a. H2O b. CO2 c. HCl d. O225. Relative permittivity of vacuum

a. 3 b. 2 c. 1 d. 0

26. Van de graff generator can produce a potential difference of

a. 109 V b. 108 V c. 107 V d. 106 V

27. Potential at a point due to a point charge is

a.

r

q

04 b.

r

q

0

2

4 c. 2

04 r

q

d.2

0

2

4 r

q

28. Dielectric is also called as

a. conductor b. insulator c. resistor d. inductor

29. Permittivity of vocuum is


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a.9

1094

1

C2 N-1 m-2 b.

91094

1

C-2 N-1 m-2 c. 9 x 109 C2 N-1 m-2 d. 9 x 109 C-2 N-1 m-2

30. The permittivity of a medium is

a.r

o

E

Eb. Eo + Er c. EoEr d. Eo - Er

31. Electric field intensity at any point is given by,

a. E = Fq b. E =q

Fc. E =

F

qd. E = F . q

32. Unit of electric flux

a. N m2 C-1 b. N m2 C-2 c. N mC2 d. N m-2 C2

33. Lightning conductor works on the principle of

a. corona discharge b. action of sharp points c. a or b d. none

34. According to Garss law,

a.o

q

= b.

o

q

=

c.

qo= d. oq +=

35. A device not working on the principal of electrostatic induction

a. van de graff generator b. microwave oven c. a or b d. lighting

36. When two capacitors are connected in series to a source of emf then each of them will have the same

a. voltage b. electric field c. both a and b d. charge

37. If medium between two charges is replaced by air, then the force between thema. increases b. decreases c. becomes zero d. remains constant

38. If a Grausssian surface encloses a dipole 2qd, then the total flux through the surface is

a.o

q

b. o

q

2c.

o

q

2d. zero

39. Action of points is used in

a. dynamo b. lightning conductor c. van de graff generator d. both b and c

40. When air medium in a capacitor is replaced by a medium of dielectric r, then the capacity

a. decreases r times b. increases r times c. remains content d. increases r2 times

41. An example of polar molecule is

a. N2 b. H2 c. O2 d. H2O

42. If a dipole is placed at angle in a non-uniform magnetic field,

a. there is net force only b. there is a torque only

c. there is a net force in addition to torque d. there is neither a net force nor a torque

43. Two charges 10-6 and 10-7 repel each other with a force of 400N. The distance between them is

a. 0.16mm b. 1.5 mm c. 15 mm d. 0.5 m

44. The potential difference between two paralled plates of parallel plate capacitor is 100 V. Electric field between them is

104 v/m. The distance between them is,

a. 1 mm b. 1 m c. 10 cm d. 1 cm

45. Two plates of a parallel plate capacitor are separated by a distance of 1 mm of the capacitance is 8.854f then thearea of the plates is

a. 10-3 m2 b. 10 m2 c. 103 m2 d. 10-2 m2

46. The work done in moving a charge of 2 c between two points having different potentials 110 V and 220 V isa. 22 x 10-4 J b. 2.2 x 104 J c. 22 x 104 J d. 2.2 x 10-4 J

47. Two capacitors of capacitance 200 pf and 600 pf are in parallel and then charges to a potential of 120V then the value

of total charge

a. 24 x 10-9 C b. 96 x 10-9 C c. 48 x 10-9 C d. 72 x 10-9 C

48. The intensity of electric field that produce a force of 10N on a charge 5 C is

a. 2 N C-1 b. 50N C-1 c. 5 N C-1 d. 0.5 N C-1

49. If two identical point charges separated by 3m experience a force of 10 N, then the value of each charge is

a. 0.1 C b. 10 C c. 1 C d. 10-4 C50. The moment of an electric dipole is 1.2 x 10-9 cm. The charge of dipole

a. 3.6 C b. 40 C c. 3.6 x 10-12C d. 0.4 C51. The equivalent capacitance of two capacitors in series is 1.5 f. The capacity of one is 4f, the value of the other is

a. 2.4

f b. 0.24

f c. 0.417

f d. 4.17

f52. In the circuit below, the value of each capacitor is 1f, the effective capacity between the points P and Q is

a.

2

3 f b.

5

2 f c.

6

5f d.

3

2 f

53. If a capacitor of capacitance 55pf is charged to 1.6v, then the number of charges on the negative plate is

a. 55 x 107 b. 5.5 x 107 c. 550 x 107 d. 0.55 x 107


Std : XII Physics Lesson II (One mark questions)


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1. A charge of 60C passes through an electric lamp for 2 minutes. Then the current through the lamp is

a. 30 A b. 1A c. 0.5 A d. 5 A

2. The material through which electric current can flow easily

a. quartz b. mica c. germanium d. copper

3. The current flowing through a conductor is proportional to

a. drift velocity b.sectioncrossofarea

1c.

electronsofnumber

1d. square of area of cross section

4. A toaster operating at 240V has a resistance of 120 ohms. The power is,

a. 400w b. 2w c. 480w d. 240w

5. If a certain length of a copper wire has certain resistance R, then on doubling the length, is specific resistance

a. will be doubbed b. will become4

1th c. will become 4 times d. will remain the same

6. When two 2 ohm resistances are in parallel the effective resistance isa. 2 ohm b. 4ohm c. 1 ohm d. 0.5 ohm

7. In the case of insulators, as the temperature decreases, resistivity

a. decreases b. increases c. remains constant d. becomes zero

8. According the Faradays Law of electrolysis, when a current is passed the mass of ions deposited on the electrode is

independent of

a. current b. charge c. time d. resistance

9. When n resistors of equal resistance R are connected in series, the effective resistance is

a.Rn b.

nR c.

nR

1d. nR

10. When n resistors of equal resistance R are connected in parallel, the effective resistance is

a.R

nb.

n

Rc.nR

1d. nR

11. Free electrons are very loosely attached to the

a. nuclei b. protons c. atoms d. neutrons

12. The thermodynamic internal energy of the materials is sufficient to liberate

a. inner electrons b. outer electrons c. protons d. neutrons13. The external energy required to drive the free electrons in a definite direction is called

a. current b. resistance c. emf d. power

14. If a charge of q coulomb passes through a conductor in time I seconds, then the current is given by,

a. I = qt b. I =qt c. I =

tq d. I =

qt1

15. Force experienced by a free electron in an electric field E is

a. Ee b.E

ec.e

Ed. Ee2

16. Accebration experienced by a free electron of mass m and charge e in an electric field E is

a. a =m

eTb.

m

eEc.

m

Ed.

e

m

17. Expression for mobility is

a.m

Eeb. T

m

Ec.

m

ed.

T

me

18. The unit of mobility is _____ a. m2VS-1 b. m2V-1S c. m2V-1S-1 d. m-2VS-119. Drift velocity of electron is proportioned to

a. electric field on intensity b. charge of protons c. are of the conductor d. none of these

20. Drift of the electrons is of the order of

a. 0.2 cm b. 0.1 cm / sec c. 0.1 m s-1 d. 1cm / sec

21. Unit of current density is

a. Am-2 b. Am-1 c. Am d. mA-2

22. The relation between current and drift velocity is

a. I = nJe dv b. I =n

Aev d c. I = nA dv e d. I = ne dv

23. Relation between current density and drift velocity

a. I = Jne dv b. dv = Jne c. dv = neJA d. I = ne dv

24. Expression for electrical resistance R is

a. R =

2nAe

mLb. R =

2mAenL

c. R =mL

nAe 2

d. R =

2nAe

mLv

25. The current through a conductor is proportional to

a. length of conductor b. charge of conductor c. e2 d. e3

26. Reciprocal of resistance is

a. resistively b. conductivity c. conductance d. inductance

27. Unit of conductance is

a. ohm b. ohm meter c. mho d. mho met-1

28. Unit of resistively isa. ohm b. ohm meter c. mho d. mho met-1

29. Unit of conductivity is

a. ohm b. ohm meter c. mho d. mho met-1


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30. The resistance of a conductor of unit length having unit area of gross section

a. conductance b. capacitance c. resistivity d. conductivity

31. The reciprocal of resistively is

a. conductance b. inductance c. resistivity d. conductivity

32. The conductivity of a material is obtained by the relation

a.L

RA= b.

R

LA= c.RA

L= d.

R

lA=

33. Materials having resistivity of the order of 10-6 ohm meter to 10-8 ohm meter are

a. insulator b. conductors c. semi conductors d. none of the above

34. Resistivity of conductors of the order of 108 ohm meter to 1014 ohm meter are called

a. insulators b. conductors c. semi conductors d. none of these

35. Semi conductors have resistivity of the order ofa. 108 to 1014 ohm meta b. 10-6 to 10-8 ohm meta c. 10-2 to 104 ohm meter d. 10-2 to 10+2 ohm meta

36. Resistively of mercury is zero at

a. 2.4 K b. 4.2 K c. 2.4oC d. 4.2oC

37. At transition temperature the electrical resistivity drops to

a. zero b. maximum c. just above zero d. none of these

38. At transition temperature, the conductivity becomes,

a. zero b. infinity c. maximum d. none of these

39. The care of the carbon resistance is made of

a. carbon b. silver c. ceramic d. iron

40. The tolerone of silver, gold, red and brown in carbon resistors are respectively.

a. 1%, 2%, 5% and 10% b. 10%, 2%, 5%, 1% c. 10%, 5%, 1% and 2% d. 10%, 5%, 2%, 1%

41. The tolerance of carbon resistor without a colour ring is

a. 20% b. 10% c. 2% d. 25%

42. Colour code for 1 in carbon resistors is,

a. Black b. brown c. silver d. red

43. In the carbon resistor, the third coloured ring indicates

a. fist significant figure b. tolerance c. power of 10 to be multiplied d. second significant figure

44. The formula for effective resistance for several resistances in series is

a. Rs =1

1

R+

2

1

R b.

SR

1= R1 + R2 c.

SR

1=

1

1

R+

2

1

R d. R s = R1 + R2

45. The reciprocal of effective resistance of resistances in parallel is

a. RP =R1 + R2 b.PR

1=

1

1

R+

2

1

R c.

PR

1= R1 + R2 d.

PR

1=

2

1

R

R

46. The effective resistance of two resistances in parallel is

a. RP =21

21

RR

RR

+b. RP =

21

21

RR

RR +c. RP =

1

1

R-

2

1

Rd. RP = R1 + R2

47. If Ro and Rt are the resistances of a conductor at 0oC then temperature coefficient of resistance is,

a.to

o

RR

ER

= b.tR

RR

o

toc.

tR

RR

o

tc d.

tR

RR

c

ot

48. If the resistance of a material increases with temperature them the temperature coefficient of resistance is

a. zero b. negative c. positive d. none of these49. The temperature coefficient of resistance for insulators and semi conductors

a. positive b. negative c. low d. zero

50. The material with negative temperature coefficient of resistance is called

a. metal b. alloy c. thermistor d. thermometer

51. Due to ageing, the internal resistance of a cell

a. increases b. decreases c. does not change d. becomes zero

52. The temperature coefficient of resistance for managain and constantan is

a. infinity b. high c. low d. high

53. The internal resistance of a cell can be calculated using the formula,

a. r = RI

VE

b. r = RV

VE

c. r = RE

VE

d. r = RI

tE

54. The condition for bridge balance in wheatstones bridge is

a.Q

R

S

P= b. PR = QS c. PS = QR d. PR = RS

55. Equation for electric power is

a. P = Vit b. P = VI c. P = V2R d. P = I2Rt

56. Equation for electriced energy a. I2Rt b. I2R c. V2Rt d.Rt

V2

57. One kilo watt hour is equal is

a. 3.6 x 105J b. 0.36 x 105J c. 36 x 105J d. x 103J

58. The positive ions which are mostly formed from metals or hydrogen are called

a. anions b. cations c. positive particles d. atoms

59. When one ccorclemeb of charge is passed through an electrolyte, the mass of the substance liberated is calleda. a weight b. electro chemical equivalent c. current d. electrical resistance

60. Unit of electro chemical equivalent is

a. CKg-1 b. KgC c. KgC -2 d. KgC-1

61. The electrodes used in voltaic cell are


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a. Cu, Zn b. Cu, Fe c. Fe Zn d. Cu, C

62. The potential difference between the two electrodes of voltaic cell are

a. 1.5V b. 1.8V c. 1.08V d. 1.58V

63. The emf of lechleanche cell is

a. 1.08V b. 1.5V c. 1.05V d. 1.1V

64. Lechlanche cell can supply a current of

a. 0.25A b. 0.5A c. 2.5A d. 5.2A

65. In secondary cell, the process of producing active materials is called

a. charging b. discharging c. specific gravity d. internal resistance

66. Electrolyte used in lead acid accumulator isa. lead acid b. HCl c. dilute H2SO4 d. HNO3

67. The electrolyte used in lechlanche cell is

a. dil H2SO4 b. NH4Cl c. HCl d. HNO368. The EMF of lead acid accumulator under freshly charged and discharge condition are

a. 2.2V and 2 V b. 2 V and 2.2 V c. 2.2V and 1.35V d. 2V and 1.35V69. The value of EMF developed and specific gravity of the electrolyte in lead accumulator are

a. 1.95V and 1.35 b. 2.2V and 1.35 c. 1.35V and 1.9 d. 2.2V and 1.28

70. While on charging and discharging the specific gravity of the electrolyte in lead acid accumulator are

a. 1.28V and 1.12 b. 1.12 and 1.28 c. 1.9 and 1.28 d. 2 and 2.2

71. A charge of 1 C passes through an electrical equipment in 10s, then the current flowing through it is

a. 0.54 b. 1A c. 0.1A d. 10a

72. The making of at the bottom of a take recordor are 9V, 450mA. Then the net resistance of the tape recorder.

a. 20ohm b. 200ohm c. 2 ohm d.20

1ohm

73. An electrical instrument of R = 30 ohms is operated at 240V. The power is

a. 240W b. 1290W c. 920W d. 1920W

74. If two resistance of 200 ohm and 0.1 kilo ohm are in series, the efficiencies resistance is

a. 200.1ohm b. 300 ohm c. 201 kilo ohms d. 2.1 K. ohms

75. If 6.25 x 1018 electrons flow through a conductor in unit time, then the current is

a. 1A b. 2A c. 0.1A d. 0.04A76. An electric lamp is operated at 240V and the current is 0.5A, then the resistance of lamp is

a. 840 ohm b. 480 ohm c. 240 ohm d. 380 ohm

77. A cell has a potential difference of 6 V in open circuit. It drops to 4 V what is internal resistance of cell? When a

current of 0.2A is drown

a. 1 ohm b. 10 ohm c. 0.1 ohm d. 2 ohms

78. The resistance of a wire of 1m length and area 0.034 mm2 cross section & resistivity 1.7 x 10-8 ohm meter is

a. 0.5 ohm b. 5.0 ohm c. 2 ohm d. 0.05 ohm

79. The number of electrons flowing per second flowing through a conductor carrying a current of 3.2 A is

a. 2 x 1019 b. 3 x 1018 c. 6.25 x 1018 d. 6.25 x 1019

80. A 1.5 KW and 230V water heater can draw a current of

a. 2A b. 0.2A c. 5A d. 0.5A

81. The ratio of diameters of two copper wires of 2m and 8m having equal resistances is,

a. 2 : 1 b. 1 : 2 c. 2 : 8 d. 1 : 6

82. Three resistances of values, 10 ohms , 2ohms and 3ohms are connected to form the sides of a triangle, AB, BC and

CA respectively. The effectiv3e resist between A and B is

a. 3.33 ohms b. 2.33ohms c. 3.5 ohms d. 3.9 ohms83. In wheatstones bridge under bridge balance condition, the four resistances of the four arms in cylic order

a. 5, 10, 4, 8 b. 5, 10, 8, 4 c. 5, 8, 10, 4 d. 5, 4, 8, 1084. Two resistances 6 ohm and 4 ohm are connected in parallel and the combination is connected in series with a resist of

2.6 ohms and an accumulator of emf 2v. The current in the circuit is

a. A2

5b. A

4

5c. A5

2d. 5A

85. In a meter bridge a resistance of 5 ohm in the right gap, the ratio of balancing length is 3 : 2. The value of other

resistance is

a.3

10ohm b.

9

10ohm c.

2

15ohm d.

5

3ohm

86. In potentiometer experiments, the balancing lengths of two cells are 250 cms & 750 cms respectively. EMF of I cell is2V. Then EMF of II cell is

a. 6V b. 4V c.3

2V d.

2

3V

87. A 750 W iron box is used for 4 hours. If the cost per unit is 75 paise, the total expense is

a. Rs. 22.50 b. Rs. 5.25 c. Rs. 2.25 d. Rs. 3.00

88. Value of a carbon resistor with the colour code yellow, violet, orange is

a. 37 kilo ohms b. 47 kilo ohms c. 4.7 ohms d. 3.7 kilo ohms

89. The value of a carbon resistor is 33 K. ohms. The colour code isa. brown, yellow, orange b. yellow, orange, red c. red, blue, orange d. orange, orange, orange

90. The resistance of a coil is 4 ohms at 0oC and 6 ohms at 100oC. Then the temperature coefficient of resistance is

a. .003/oC b. 0.004/oC c. 0.005/oC d. 0.006/oC


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Std : XII Physics Lesson III (One mark questions)

1. Joules law of heating is

a. H = tR

I2b. H = V2 Rt c. H = VIt d. H = IR 2t

2. Nichrome wire is used as heating element because it has

a. high specific resistance b. low melting point c. low specific resistance d. high conductivity

3. Peltier coefficient at the junction of a thermocouple depends on

a. the current in the thermocouple b. the time for which current flowsc. the temperature of the junction d. the charge that passes through the thermocouple

4. In a thermocouple, the temperature of the cold junction is 20oC, Neutral temperature is 270oC. Then the temperature of

inversion is,

a. 520oC b. 540oC c. 500oC d. 510oC

5. Which of the following represents Biot savart law

a. dB =24 r

Idlo

b. dB =

24 r

Idso

c.

2r

rxIdldB

=d.

3r

rxIdldB

=

6. The magnetic induction due to a long straight conductor placed in a medium of per meabiling is,

a.a

Io

4b.

a

Io

2c.

a

I

4d.

a

I

2

7.In a T.G., for a constant current the deflection is30. The place of the coil is turned through 90. Now for the

same current, the deflection will be

a. 30 b. 60 c. 90 d. 0

8. The period of revolution of a charged particle inside a cyclotron does not depend

a. magnetic induction b. the charge of the particle c. the velocity of the particle d. mass of the particle

9. The torque on a rectangular coil placed in a uniform magnetic field is large whena. number of terms is large b. number of turns is less

c. the place of the coil is perpendicular to the field d. the area of the coil is small.

10. Phosphor be wire is used for suspension in a moving coil galvanometer because it has

a. high conductivity b. high resistively c. large couple per unit twist d. small couple per unit twist11. of the following devices which has small resistance

a. moving coil galvanometer b. ammeter of range 0 to 1A c. ammeter of range 0 to 10A d. voltmeter

12. A galvanometer of resistance G ohm shunted with S ohm. The resistance Re. Then which of the followingstatements is true.

a. G is less than S b. S is less than R e but greater than G

c. Re is less than both G and S d. S is less than both Re and G.13. An ideal voltmeter has

a. finite resistance less than G but greater than zero b. zero resistance

c. resistance greater than G but less than infinity. d. infinity resistance.14. For a steady current I, the amount of heat produced in time t is

a. H = VIt b. V2It c. VI2t d.Vt

15.Accoridng to Joules law of heating for a given R, heat produceda. directly proportional to square of current b. inversely proposition to square of current

c. directly proportional to the current d. inversely proportional to current.

16. of the following which is wrong?

a. H i2 for a given R b. H R for a given I c. H V for a given R d. 1 + 1/R 17. Nichrome is an alley of

a. nickel, chromium and manganeseb. nickel, cobalt and iron c. nickel and iron d. nickel and chromium

18. Nichrome is used as heating element becausea. it has high specific resistance b. high melting point c. it is not easily oxidized d. all the above

19. Fuse wire is an alloy of

a. 37% Pb and 63%Sn b. 63% Pb and 37% tin c. 73% Pb and 27% Sn d. 37%Sb and 63% Sn

20. Melting point of Tungsten is

a. 3380C b. 338o K c. 380C d. 380K

21. Filament of an electric bulb is usually enclosed in a glass bulb containinga. inert gas at high pressure b. inert gas at low pressure

c. ideal gas at high pressure d. inert gas at low pressure

22. In which of the following Joule heating effect is undesirable

a. Electric iron b. electric toaster c. Transformer and dynamo d. fuse wire23. Which of the following is not a thermo emf effect?

a. serbeck effect b. Joule effect c. Peltier effect d. Thomson effect

24. Complimentary effect of seebeck effect isa. Peltier effect b. Joule effect c. Thomson effect d. negative Thomson effect

25. In a circuit containing two dissimilar metals, and emf is developed in the circuit when the junctions are at

a. the same temperature b. very high temperatures c. very low temperatures d. at different temperatures26. In Cu Fe thermocouple the direction of the current at the hot junction is,

a. from Cu to Fe b. from Fe to Cu c. either a or b depending on the temp of hot junction d. random direction


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27. temperature dependence of a thermo couple is given by,

a. V=2

2

1+ b. V= )( + c. V= a 3

2

1+ d. V= 42 +

28. For a given thermocouple the temp of inversion

a. is a constant b. depend on the temperature of cold junction

c. independ on the temperature of cold junction d. depend on neutral temperature29. For small difference of temperature the graph showing the variation of thermo emf with the temperature of

hot junction is a. Parabola b. circle c. straight line d. hyperbola

30. For a given thermocouple, the neutral temperature isa. a maximum b. minimum c. zero d. constant

31. The relation between the neutral temp. of inversion and temp. of cold junction is

32. Contact potential is

a. more at hot junction b. loss at hot junction c. equal at both junctions d. zero at a junction

33. A conduction with negative Thomson effect isa. silver b. zinc c. mercury d. Cadmium

34. An example of positive Thomson effect is

a. Iron b. Cobalt c. Copper d. Nickle

35. For drawing thermo electric diagram, the metal that is used as one of the two metals isa. Pl b. Copper c. Silver d. Fe

36. For purpose of drawing thermoelectric diagrams Pb is used as one of the metals in a thermo couple becausea. it has high conductivity b. high specific resistance c. high melting point d. Thomson coefficient is zero

37. For large difference of temperature, the graph showing the relation between the thermony and temperature

of hot junction isa. a straight line b. parabola c. circle d. hyperbola

38. of the following which is reversible

a. seebeck effect b. Peltier effect c. both a and b d. Joule effect

39. Unit of Peltier coefficient is

a. volt b. volt/c b. Ampere (d) ampere/c

40. The position of the metal in a thermoelectric series depends upon,a. temperature (b) nature of the metal c. magnitude of thermo emf d. atomic number of the metal41. The device used to measure thermal radiation is,

a. thermocouple b. thermopile c. thermometer d. thermoscope

42. Ina thermopile the deflection in the galvanometer is proportional to

a. intensity of radiation b. frequency of radiation c. velocity of radiation d energy of radiation

43. Magnetic induction at a point due to infinity long straight conductor carrying current at a distance from

the axis isa. directly proportional to a b. directly proportional to a2 c. inversely proportional to a d. inversely

proportional to a2

44. Tangent galvanometer works on the principle of

a. Biot savrt law b. Tangent law c. Ampere rule d. ampere circuital law45. Magnetic needle of a T.G. is kept small because the magnetic field is

a. very large at the center b. considered to be small and uniform at the center c. it is convenient to handle

small needle d. radial at the center.46. Reduction factor of a T.G. is

47. In a T.G. the plant of the coil should be adjusted to be ina. magnetic meridian b. geographical meridian c. any direction d. east west direction

48. Each section of the coil of wire in a T.G. has,

a. 1,2 and 5 turns b. 2,5and 50 turns c. 2,5 and turns d. 1,5 and 500 turns

49. The T.G. is more sensitive at,

a. 30 b. 45 c. 60 d.9050. Biot Savart law in an alternative is called

a. end rule b. Gauss law c. Amperes circuital law d. Flamings left hand rule51. In a more generalized way, amperes circuital law is expressed as,


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Physics One Mark Old