ECAT Physics Alternating Current Test Online

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1. An alternating current or voltage

Fluctuates off and on

Varies in magnitude alone

Changes its direction again and again

Changes its magnitude harmonically and reverses its direction of flow after regularly recurring intervals

2. To find the r.m.s value of an alternating current mathematically we need to have

Mean value of I²

Square root of mean value of I²

Square root of I²

Square of 1/2

3. An alternating current of r.m.s value of 4.0 A and frequency 50Hz flows in a circuit containing 10 ohm resistor. The peak current is then

20 A

20.66 A

6.66 A

5.66 A

4. If the rms voltage drop across a 15 k resistor is 16 V, the peak current through the resistor is

15 mA

1.5 mA

10 mA

1 mA

5. A sinusoidal current has an rms value of 14 mA. The peak-to-peak value is

45.12 mA

22.6 mA

16 mA

39.6 mA

6. The average value of a 12 V peak sine wave over one complete cycle is

0 V

1.27 V

6.37 V

7.64 V

7. A pure variable resistor is connected in series with a pure capacitor of fixed capacitance. The impedance of the circuit

Remains

Becomes infinite

Becomes zero

Increases

8. Ammeter connected in an AC circuit measures

Exact value of current

Rms value of current

Net value of current

Peak value of current

9. You could increase the time constant of an RC circuit by

Adding a resistor in parallel with the circuit resistance

Adding a capacitor in parallel with the circuit capacitance

Increasing the amplitude of the input voltage

Exchanging the position of the resistor and capacitor in the circuit

10. What is the total opposition to current in a series RC circuit called?

Impedance

Inductance

Reactance

Resistance

11. What is the reactance value for a capacitor installed in a dc circuit?

Zero

Moderate

Infinite

Cannot tell

12. In an ac circuit, a capacitor and an output resistor are connected in series with an ac signal. What filter action will be the result?

Band pass

Low-pass

High-pass

Band-stop

13. How is ac current related to ac voltage in purely capacitive circuit?

AC current is 0.707 of the ac voltage

AC current lags ac voltage

AC current is 0.637 of the ac voltage

AC current leads ac voltage

14. What is the impedance of an ac RC parallel circuit if the resistance is 12 ohms and the capacitive reactance equals 5 ohms?

0.2 ohms

3.5 ohms

4.6 ohms

13 ohms

15. In a series RLC circuit that is operating above the resonant frequency, the current

Is zero

Leads the applied voltage

Lags the applied voltage

Is in phase with the applied voltage

16. If the value of C in a series RLC circuit is decreased, the resonant frequency

Decreases

Increases

Is not affected

Is reduced to zero

17. In a certain series resonant circuit, Vc = 125 V, VL = 125 V, and VR = 40 V. The value of the source voltage is

125 V

250 V

290 V

40 V

18. Series RLC voltage or impedance totals must be calculated by:

Subtracting the values

Graphing the angles

Adding vectors

Multiplying the values

19. When XC = XL the circuit:

Draws maximum current

Applied voltage is zero

Is at resonance

Draws minimum current

20. How much current will flow in a series RLC circuit when VT = 100 V, XL = 160 Ω, Xc = 80 Ω, and R = 60 Ω?

1 A

1 mA

6.28 A

10 A

21. What is the true power consumed in a 30 V series RLC circuit if Z = 20 ohms and R = 10 ohms?

15.0 watts

22.5 watts

30.0 watts

45.0 watts

22. A choke is used as a resistance in

DC circuit

AC circuits

Both AC and DC circuit

Full wave rectifier circuit

23. The electrical oscillators are used in

Metal detectors

Amplifier

Diode

None of these

24. A changing magnetic flux produces around itself an induced

Magnetic field

Electric field

Electromagnetic force

Artificial gravitational field

25. Electromagnetic waves travel in free space with the speed of

Gamma-rays

Positive rays

Cathode rays

Less than sound waves

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26. The direction of propagation of an electromagnetic waves is

Perpendicular to electric field

Perpendicular to both electric and magnetic field

Perpendicular to magnetic field

Parallel to electric and magnetic field

27. An electromagnetic wave consists of

Electric and magnetic fields moving parallel to each other

Magnetic field moving with velocity of light in space

Electric field moving with velocity of light

Electric and magnetic fields moving perpendicular to each other

28. Waves emitted from the antenna are

Sound waves

Electromagnetic waves

Radio waves

Modulated waves

29. A.M stands for

Amplitude Modulation

Applied Metal

Accurate Measurement

None of these

30. F.M stands for

Frequency Modulation

Frequency Metal

Frequency Member

All of these

31. The process of combing the low frequency signal with high frequency radio-wave is called

Modulation

Amplification

Rectification

None of these

32. Which one give more quality transmission?

A.M

F.M

S.W

M.W

33. The instantaneous value of A.C voltage is given by

V = V₀ sin 2 π ft

V = V₀/sin 2 π ft

V = sin 2 π ft/V₀

V = V₀ π ft/sin 2

34. During each cycle, alternating voltage reaches a peak value

One time

Two times

Four times

A number of times depending on the frequency

35. In alternating current, the average power delivered during a cycle is

Zero

One

I² R

V/R²

36. A.D.C. ammeter measures alternating current as

Instantaneous value

Root mean square value

Peak to peak value

Average value

37. The angle θ in equation V = V₀ sin θ specifies

Average value

Instantaneous value

Root mean square value

None of these

38. The basic circuit element in D.C circuit is a

Capacitor

Resistor

Inductance

None of these

39. The device which allows only the flow of an A.C. through a circuit is

Capacitor

Inductor

D.C. motor

Battery

40. In A.C. circuits the basic elements are

Resistor

Capacitor

Inductor

All of these

41. The r.m.s value of alternation current is equal to its maximum value at angle of

60o

45o

30o

90o

42. The P = VI = I² R = V²/R holds only when the

Current lags voltage

Current leads voltage

Current and voltages are in phase

None of these

43. A resonance curve for RLC series circuit is a plot of frequency versus

Voltage

Current

Impendence

Reactance

44. In A.C. through capacitor circuit the v and q are as

v leads q

v legs q

v and q are in phase

None of these

45. The power factor of resonance series circuit is

1

0

-1

0.5

46. At high frequency the reactance of the capacitor is

Low

Large

Very large

None of these

47. At resonance, the phase angle for RLC series resonance circuit equals

0°

90°

180°

270°

48. At high frequency and low reactance the current will be

Large

Very large

Extremely large

None of these

49. At resonance, the impedance of RLC series circuit is

Maximum

Zero

Minimum

Determinate

50. An inductor is a solenoid having the resistance

Large

Small

Negligible

None of these

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51. The impedance of RLC series resonance circuit at resonant frequency is

Greater than R

Equal to R

Less than R

None of these

52. The reactance of a coil depends upon the

Frequency of A.C

Frequency of D.C

Both a and b

None of these

53. As a function of Frequency, the inductance and capacitance behaves

Similarly

Opposite

Always similar

None of these

54. SI unit of impedance is

Hertz

Henry

Ampere

Ohms

55. In pure inductor, the power dissipation is

Maximum

Minimum

Zero

None of these

56. The phase angle of a serried RLC circuit at resonance is

180°

90°

0°

45°

57. An inductor coil when consume no energy is called

A coil

Choke

Toriod

All of these

58. If the value of C in a series RLC circuit is increased, the resonant frequency

Is not affected

Increase

Remains the same

Decreases

59. In an inductor the phase difference between the current and voltage is

Current lags voltage by 90°

Voltage lags current by 180°

Current leads voltage by 90°

Current leads voltage by 180°

60. Which one of the following waves belongs to electromagnetic spectrum

Radio and TV waves

Radar waves

Micro waves

All of these

61. Power dissipation is zero in a circuit

Inductive

Capacitative

Both

None of these

62. Which one of the following electro-magnetic wave have the highest frequency and shortest wave-length

X-rays

Ultraviolet rays

y-rays, gamma rays

Cosmic rays

63. The impedance Z of the R-L series circuit is

Z = √R² + (1/ωC)²

Z = √R² + (1/ωL)²

Z = √R² + (ωL)²

Z = √R² + (ωD)²

64. Transmitting antenna emits

Magnetic waves

Electric waves

Electromagnetic waves

Sound waves

65. When electrons in the transmitting antenna vibrate 94000 times per second, they produce radio waves having frequency

9.4 kHz

940 kHz

94 kHz

9.40 kHz

66. In a three phase AC generator, three coils are connected and inclined at an angle

60°

120°

180°

90°

67. Chock consumes extremely small

Charger

Current

Power

Potential

68. Since there are three coils, the generator has the terminals

Two

Four

Six

Eight

69. In L.C.R series A.C. circuit, the phase angle between current and voltage is

Any angle between o and ± π/2

π/2

π

Any angle between 0 and π/2

70. An ideal choke (used along with fluorescent tube) would be

A pure resistor

A pure capacitor

A pure inductor

A combination of an inductor and a capacitor

71. The speak voltage in a 220 volt A.C, supply is nearly

220 volt

253 volt

311 volt

440 volt

72. In a capacitive circuit

Current leads voltage by phase of π/2

Voltage leads current by phase of π/2

Current and voltage are in same phase

Sometime current and sometime voltage leads

73. Energy is stored in the choke coil in the form of

Heat

Magnetic energy

Electric energy

Electro-magnetic energy

74. The henry is the unit for

Resistance

Magnetic flux

Magnetic field

Inductance

75. A fuse wire is having 5 ampere current rating. What is the peak value of current it can have?

0.7074 A

7.07 A

0.0707 A

7.707 A

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76. In LCR circuit which one of the following statements is correct?

L and R oppose each other

R value increase with frequency

The inductive reactance increases with frequency

The capacitive reactance increases with frequency

77. The value of current at resonance in series LCR circuit is affected by the value

R only

C only

L only

R, C and L

78. The root mean square voltage for alternating current is

Vrms = √V₀²/2

Vrms = V₀/√2

Vrms = 0.707V₀

All of these

79. The angle which specifies the instantaneous value of the alternating voltage or current is called

Phase

Critical angle

Angle of incidence

All of these

80. The highest value reached by voltage or current in one cycle is called

Root mean square value

Peak value

Peak to peak value

Instantaneous value

81. The sum of positive and negative peak values are usually written as

P-P value

Negative

Zero

May be positive or negative

82. The r.m.s. value of a.c. current is always

Positive

Negative

Zero

All of these

83. The phase at the positive peak is

π/2

π

3π/2

2π

84. The combined effect of resistance and reactance in a.c. circuit is called:

Conductance

Resistance

Impedance

Choke

85. In a three phase a.c. generator, there are

2 coils

3 coils

1 coils

No coil

86. In a three phase a.c. generator if the first coil has a phase 0, then the other two coils will have phases

90° - 120°

20° and 140°

120° and 240°

120° and 140°

87. A piece of wire along which charges are made to accelerate is known as

Transmitting antenna

Receiving antenna

Modulator

Nor of these

88. A wire is bent into a ring of radius R is given a charge q. The magnitude of the electrical field at the center of the ring is

Two

½

Zero

3/2

89. The A.M. transmission frequency range from

500-1000 KHz

540-1600 KHz

300-490 KHz

900-2040 KHz

90. A choke coil is used as a resistance in

d.c. circuit

a.c. circuit

d.c. potentiometer circuit

Wheatstone bridge

91. Which scientist experimentally proved the existence of electromagnetic waves?

Sir. J.C. Bose

Maxwell

Marconi

Hertz

92. Radio frequency choke uses core of

Air

Iron

Air and iron

None of these

93. The magnetic moment of a current (I) carrying circular coil of radius (r) and number of tums (n) varies as

1/r²

1/r

r

r²

94. A bar magnet is equivalent to

Torroid carrying current

Straight conductor carrying current

Solenoid carrying current

Circular coil carrying current

95. The current I in the circuit below is

1/45 A

1/15 A

1/10 A

1/5 A

96. Thermocouple is an arrangement of two different metals

To convert heat energy in to electrical energy

To produce more heat

To convert heat energy into chemical energy

To convert electric energy in to heat energy

97. The electric field due to an infinitely long thin wire at a distance R varies as

1/R

1/R²

R

R²

98. An electron of charge e coulomb passes through a potential difference of V volts. Its energy in ‘joules’ will be

V/e

eV

e/V

V

99. The thermistors are usually made of

Metals with low temperature coefficient of resistivity

Metals with high temperature coefficient of resistivity

Metals oxides with high temperature coefficient of resistivity

Semi conducting materials having low temperature coefficient of resistivity

100. The Current provided by a battery is maximum when

Internal resistance equal to external resistance

Internal resistance is greater than external resistance

Internal resistance is less then external resistance

None of these

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101. Equal charges are given to two spheres of different radii. The potential will

Be more on the smaller sphere

Be more on the bigger sphere

Be equal on both the sphere

Depend on the nature of the material of the sphere

102. The electric field, magnetic field and the direction of their propagation are mutually

Perpendicular

Parallel

A and B

None of these

103. The L-C parallel circuit the capacitor draws a

Leading current

Lagging current

Main current

None of these

104. Alternating current instead of direct current is used in long distance electric transmission because

It is easy to generate

Rectification is possible

Energy losses are minimum

It causes fewer accident

105. Eddy currents are used in

Induction furnace only

Electromagnetic brakes only

Speedometers only

All of these

106. The materials suitable for making electromagnets should have

High retentivity and high coercivity

Low retentivity and low coercivity

High retentivity and low coercivity

Low retentivity and high coercivity

107. Liquid oxygen remains suspended between two pole faces of a magnet because it is

Diamagnetic

Paramagnetic

Ferromagnetic

Antiferromagnetic

108. When three identical bulbs of 60 watt, 200 volt rating are connected in series to a 200 volt supply, the power drawn by them will be

180 watt

10 watt

20 watt

60 watt

109. In Pakistan electricity is supplied for domestic use at 220 V. It is supplied at 110 V in USA. If the resistance of a 60 W bulb for use in Pakistan is R, the resistance of a 60 W bulb for use in USA will be

2R

R/4

R/2

R

110. If a charged spherical conductor of radius 10 cm has potential V at a point distance 5 cm from its center, then the potential at a point distance 15 cm from the center will be

1/3 V

2/3 V

3/2 V

3V

111. If the distance of separation between two charges in increased, the electrical potential energy of the system will

Increase

Decrease

May increase or decrease

Remain the same

112. A cube of metal is given a positive charge Q. For the above system, which of the following statement is true?

Electric potential at the surface of the cube is zero

Electric potential within the cube is zero

Electric filed is normal to the surface of the cube

Electric field varies within the cube

113. A piece of wire along which charges are made to accelerate is known as

Transmitting antenna

Receiving antenna

Modulator

None of these

114. The process of combining low frequency signal with a high frequency radio wave is called

Demodulation

Modulation

Resonance

None of these

115. The time taken by AC of 50 Hz in reaching from zero to the maximum value is

1 x 10¯² s

2 x 10¯² s

50 x 10¯³ s

5 x 10¯³ s

116. The peak value of alternating current is 5√2 ampere. The mean square value of current will be:

5A

2.5 A

5√2 A

None of these

117. A beams of electrons and protons move parallel to each other in the same direction, then they:

Attract each other

Repeal each other

No relation

Neither attract nor repel

118. A proton and an α-particle are projected normally into a magnetic field. What will be the radii of the trajectories of the proton and α particle?

2 : 1

1 : 2

4 : 1

1 : 4

119. The resistivity of wire depends upon:

Its material

Its shape

Its length

Its area of cross section

120. The equivalent resistance and potential difference between A and B for the circuit is respectively:

4 Ω, 8 V

8 Ω, 4 V

2 Ω, 2 V

16 Ω, 8 V

121. The volt is equal to

C/q

N/m²

Joule/coulomb

Nm²/C

122. Two conductors having the same type of charges are connected by a conducting wire. There would not be any amount of charges on them if

They have the same potential

They have the same amount of charge

They have the same capacity

They have the same shape

123. In a three phase a.c. generator, there are

2 coils

3 coils

1 coils

No coil

124. In a three phase a.c. generator if the first coil has a phase 0, then the other two coils will have phases

90° - 120°

20° and 140°

120° and 240°

120° and 140°

125. Two coils are placed close to each other. The mutual inductance of the pair of coils depends upon:

The currents in the two coils

The rates at which currents are changing in the two coils

Relative position and orientation of the two coils

The materials of the wires of the coils

Page 6 of 10

126. The core of any t4ansformer is laminated so as to

Increase the secondary voltage

Reduce the energy loss due to eddy currents

Make it light weight

Make it robust and strong

127. Some charge is being to a conductor. Then its potential

Is maximum at surface

Is maximum at center

Is remain same throughout the conductor

Is maximum somewhere between surface and center

128. At any point on the right bisector of the line joining two equal and opposite charges

At electric field is zero

The electric potential is zero

The electric potential decrease with increasing distance from the center

The electric field is perpendicular to the line joining the charges

129. The electric potential at the surface of an atomic nucleus (Z = 50) of radius 9.0 x 10¯¹⁵ m is

9 x 10⁵ V

9 V

8 x 10⁶ V

80 V

130. 20 ampere current is flowing in a long straight wire. The intensity of magnetic field at a distance 10 cm from the wire will be:

4 x 10¯⁵ Wbm¯²

9 x 10¯⁵ Wbm¯²

8 x 10¯⁵ Wbm¯²

6 x 10¯⁵ Wbm¯²

131. An electron moves at right angle to magnetic field 0f 1.5 x 10¯² tesla with a speed of 6 x 10⁷ m/s. if the specific charge of the electron is 17 coul. /kg, the radius of the circular path will be:

2.9 cm

3.9 cm

2.35 cm

2 cm

132. In bringing an electron towards another electron, electrostatic potential energy of system:

Decreases

Increases

Remains uncharged

Becomes zero

133. Electric potential of earth is taken to be zero because the earth is good:

Semiconductor

Conductor

Insulator

Dielectric

134. Battery is charged in motor cars, which is based on:

Chemical effect

Magnetic effect

Electric effect

None of these

135. Which of the following does not obey Ohm’s law?

Copper

Al

Diode

None of these

136. A proto is about 1840 times heavier than an electron. When it is accelerated by a potential difference of 1 kV, its kinetic energy will be:

1840 keV

1/1840 keV

1 keV

920 keV

137. For a parallel resonant circuit at resonance, current from supply is

Minimum

Maximum

Zero

None of these

138. Two inductors each of inductance L are joined in parallel. Their equivalent inductance will be:

Zero

L/2

L

2L

139. Eddy currents may be reduced b using:

Laminated core of steel

Laminate core of soft iron

Thick piece of cobalt

Thick piece of nickel

140. An alpha particle is accelerated through a potential difference of 10⁵ volt. Its kinetic energy will be

1 MeV

2 MeV

4 MeV

8 MeV

141. On moving a charge of 20 coulombs by 2 cm, 2 J of work is done, then the potential difference between the points is

0.1 V

8 V

2 V

0.5 V

142. A long solenoid carrying a current produces a magnetic field B along its axis. If the current is doubled and the number of turns per cm is halved, the new value of the magnetic field is:

B

2B

4B

B/2

143. The electric current in a circular coil of two turns produced a magnetic induction of 0.1 T at its center. The coil is unwound and is rewound into a circular coil of four turns. The magnetic induction at the center of the coil now is, in tesla, (if same current flows in the coil)

0.2

0.4

0.6

0.8

144. A resistance of galvanometer G = 6 Ω, maximum current of 2 amp is measured by it. Then required resistance to convert it into an ammeter reading up to 6 A, will be:

5 Ω

4 Ω

3 Ω

2 Ω

145. An ammeter reads up to 1 ampere. Its internal resistance is 0.81 ohm. To increase then range to 10 A the value of the required shunt is:

0.09 Ω

0.03 Ω

0.3 Ω

0.9 Ω

146. A capacitor is charged with a battery and then it is disconnected. A slab of dielectric is now inserted between the plates, then

The charge in the plates reduces and potential difference increase

Potential difference between the plates increases, stored energy decreases and charge remains the same

Potential difference between the plates decreases, stored energy decreases and charge remains unchanged

None of these

147. Two copper wires are of same length one of them is twice as thick as the other. Then the resistance of the two wires are in the ratio of:

1 : 16

1 : 8

1 : 4

1 : 2

148. Two wires of the same dimensions but resistivities p₁ and p₂ are connected in series. The equivalent resistivity of the combination is

2(p₁ + p₂)

√p₁p₂

p₁ + p₂/2

p₁ + p₂

149. If we increase the distance between two plates of the capacitor, the capacitance will

Increase

Decrease

Remain same

First increase then decrease

150. A parallel plate capacitor is first charged and then a dielectric slab is introduced between the plates. The quantity that remains unchanged is

Charge Q

Potential V

Capacity C

Energy U

Page 7 of 10

151. The power dissipation in a pure inductive or capacitance circuit is

Maximum

Positive

Zero

None of these

152. The circuit in which current and voltage are in phase, the power factor is

Zero

1

Negative

0.83

153. Eddy current is produced when

A metal is kept in varying magnetic field

A metal is kept in the steady magnetic field

A circular coil is placed in a magnetic field

Through a circular coil, current is passed

154. The energy stored in an inductor is

Electrostatic

Electromagnetic

Magnetic

Mechanical

155. The peak value of AC voltage on a 220 V mains is:

240 √2 V

230 √2 V

220 √2 V

200 √2 V

156. Force acting upon a charged particle kept between the plates of a charged condenser is F. If one of the plates of the condenser is removed, force acting on the same particle will become

Zero

F/2

F

2F

157. Energy per unit volume for a capacitor having area A and separation d kept at potential difference V is given by

½ ε₀ V²/d²

1/2ε₀ V²/d²

½ CV²

Q²/2C

158. A proton, an electron and an α particle accelerated through the same potential difference enter a region of uniform magnetic field, moving at right angles to the magnetic filed B. The ratio of their kinetic energies is:

2 : 1 : 1

2 : 2 : 1

1 : 2 : 1

1 : 1 : 1

159. A current loop of area 0.01 m² and carrying a current of 10 A is held perpendicular to a magnetic field of intensity 0.1 T, the torque acting on the loop (in N-m) is

1.1

0.8

0.001

0.01

160. The resistance of an incandescent lamp is

Smaller when switched on

Greater when switched off

The same whether it is switch off or switch on

Greater when switched on

161. The minimum resistance that can be obtained by connecting 5 resistance of ¼ Ω each is

4/5 Ω

5/4 Ω

20 Ω

0.05 Ω

162. A medium of dielectric constant ‘K’ is introduced between the plates of parallel plate condenser. As a result its capacitance

Increase k time

Decreases k times

Decreases 1/k times

Remains unchanged

163. Units of impedance are

Henry

Ohms

Moh

Watt

164. Such an inductor coil which does not consume energy and is often employed for controlling a.c. without consumption of energy is called

Choke

Impedance

Semi-conductor

None

165. The ratio of the r.m.s. value of the applied voltage to the r.m.s. value of resulting a.c. is

Impedance

Inductance

Reactance

Resistance

166. A one microfarad capacitor of a TV is subjected to 4000 V potential difference. The energy stored in capacitor is

8 J

16 J

4 x 10¯³ J

2 x 10¯³ J

167. A parallel plate condenser with oil between the plates (dielectric constant of oil k = 2) has a capacitance C. If the oil is removed, then capacitance of the capacitor becomes

√2C

2C

C/√2

C/2

168. A metal plate of thickness half the separation between the capacitor plates of capacitance C is inserted. The new capacitance is

C

C/2

Zero

2C

169. A condenser of capacity 50 μF is charged to 10 V. The energy stored is

1.25 x 10¯³ J

3.75 x 10¯³ J

2.5 x 10¯³ J

5 x 10¯³ J

170. The average power dissipated in a pure inductor of inductance L is

LI²/2

LI²

LI²/4

Zero

171. The electromagnetic waves travel with a velocity

Equal to velocity of sound

Equal to velocity of light

Less than velocity of light

None of these

172. The velocity of electromagnetic wave is parallel to

B x E

E x B

E

B

173. An α-particle enters a magnetic field of 1 tesla with a velocity 10⁶ m/s in a direction perpendicular to the field. The force on α-particle is

1.6 x 10¯¹³ N

6.4 x 10¯¹³ N

4.8 x 10¯¹³ N

3.2 x 10¯¹³ N

174. A correct carrying loop is placed in a uniform magnetic field. The torque acting on it does not depend on

Shape of the loop

Area of the loop

Number of turns in the loop

Strength of the current

175. A superconductor exhibits perfect

Ferromagnetism

Ferrimagnetisms

Diamagnetism

Paramagnetism

Page 8 of 10

176. The capacity of a condenser, when a dielectric is placed in between its plates

Increases

Decreases

Does not change

None

177. In a charged capacitor the energy is stored in

Both in positive and negative charges

Positive charges

The edges of the capacitor plates

The electric field between the plates

178. A heater coil rated at (1000 W – 200 V) is connected to 110 volt line. What will be the power consumed?

200 W

302.5 W

250 W

350 W

179. A current of 1.6 A is passed through a solution of CuSO₄. How many Cu²⁺ ions are liberated in one minute?

3 x 10²⁰

3 x 10¹⁰

6 x 10²⁰

6 x 10¹⁰

180. When a wire is stretched and its radius becomes r/2, then its resistance will be

16 R

4 R

2 R

0

181. Current varies with voltage

Inversely

As square root

Directly

None of these

182. The reactance of a coil changes directly with

Frequency of a.c.

The inductance

Both a and b

None of these

183. The combined effect of resistance and reactance’s in a.c. circuit is called

Conductance

Resistance

Impedance

Choke

184. In a pure inductive circuit, current

Lags behind e.m.f by π/2

Lags the e.m.f by π/2

Lags behind by π

Leads the e.m.f by π

185. Alternating current is transmitted to distant places

At high voltage and low current

At high voltage and high current

At low voltage and low current

At low voltage and high current

186. A capacitor is perfectly insulator for

Direct current

Alternating current

Direct as well as alternating current

None of these

187. Field inside a solenoid is

Directly proportional to its length

Directly proportional to current

Inversely proportional to number of turns

Inversely proportional to current

188. To convert a moving coil galvanometer into voltmeter the value and type of connection of the resistance to be connected with should be

Low ad parallel

High and parallel

Low and series

High and series

189. Which of the following statements is incorrect about hysteresis?

This effect in common to all ferromagnetic substances

The hysteresis loop area is proportional to the thermal energy developed per unit volume of the material

The hysteresis loop area is independent of the thermal energy developed per unit volume of the material

The shape of the hysteresis loop is characteristic of the material

190. An electron is projected along the axis of a circular conductor carrying some current. Electron will experience force

Along the axis

Perpendicular to the axis

At an angle of 4° with axis

No force experienced

191. The capacity of a parallel plat capacitor depends on the

Type of metal used

Thickness of plates

Potential applied across the plates

Separation between the plates

192. If the distance between the plates of a parallel plate condenser of capacity 10 μF is doubled then new capacity will be

5 μF

20 μF

10 μF

15 μF

193. A capacitor of capacity 1 μF is charged to 1 kV. The energy stored in J

5

0.5

0.005

50

194. For two resistance wires joined in parallel, the resultant resistance is 6/5 ohm. When one of the resistance wire breaks, the effective resistance becomes 2 ohm. The resistance of the broken wire is

3/5 ohm

2 ohm

6/5 ohm

3 ohm

195. In the figure a carbon resistor has bands of different colours on its body as mentioned in. The value of the resistance is

2.2 k Ω

3.3 k Ω

5.6 k Ω

9.1 k Ω

196. The colour sequence in a carbon resistor in red, brown, orange and silver. The resistance of the resistor is

21 x 10³ ± 10%

23 x 10¹ ± 5%

21 x 10³ ± 5%

12 x 10³ ± 5%

197. When a dielectric material is introduced between the plates of a charged condenser the electric field between the plates

Decreases

Increases

No change

May increase or decrease

198. The energy required to charge a capacitor of 5 μF by connecting D.C. source of 20 kV is

10 kJ

5 kJ

2 kJ

1 kJ

199. The average value of current and voltage over a cycle is

Positive

Negative

Zero

May be positive or negative

200. The basic circuit element in a.d.c. circuit is a/an

Inductor

Resistor

Capacitor

Battery

Page 9 of 10

201. A coil of R = 10 Ω and L = 5 H is connected to a 100 V battery, then energy stored is

100 J

400 J

250 J

500 J

202. An air core solenoid has 1000 turns and is one meter long. Its cross-sectional are is 10 cm². Its self inductance is

0.1256 mH

12.56 mH

1.256 mH

125.6 mH

203. During current growth in a L-R circuit the time constant is the time in which the magnitude of current becomes

I⁰

I⁰/2

0.63I⁰

0.37I⁰

204. Which particles will have minimum frequency of revolution when projected with the same velocity perpendicular to a magnetic field?

Li⁺

Electron

Proton

He⁺

205. If the current is doubled, the deflection is also doubled in

A tangent galvanometer

A moving coil galvanometer

Both A and B

None of these

206. Calculate the amount of charge flowing in 2 minutes in a wire of resistance 10 Ω when a potential difference of 20 V is applied between its ends.

120 C

240 C

20 C

4 C

207. A uniform resistance wire of length L and diameter d has a resistance R. Another wire of same material has length, 4L and diameter 2d, the resistance will be

2 R

R

R/2

R/4

208. A sheet of aluminum foil of negligible thickness is introduced between the plates of a capacitor. The capacitance of the capacitor:

Increases

Decreases

Remain unchanged

Becomes infinite

209. The nature of capacity of electrostatic capacitor depends on

Shape

Size

Thickness of plates

Area

210. Taking the earth to be a spherical conductor of diameter 12.8 x 10³ km. Its capacity will be:

711 μF

611 μF

811 μF

511 μF

211. In the figure below, the charge on 3 μF capacitor is

5 μF

10 μF

3 μF

6 μF

212. The sum of positive and negative peak values are usually written as

P-P value

Negative

Zero

May be positive or negative

213. The r.m.s. value of a.c. current is always

Positive

Negative

Zero

All of these

214. The phase at the positive peak is

π/2

π

3π/2

2π

215. The capacitors 2 μF and 4 μF are connected in parallel. A third capacitor of 6 μF capacity is connected in series. The combination is connected across a 2 μF capacity is

2V

6V

8V

1V

216. The equivalent capacitance of the following combination is

10 μF

4 μF

25 μF

15 μF

217. The number of turns in the coil are doubled, the emf will get

Doubled

Halved

Quadrupled

None of these

218. A choke coil is used in

A.C. circuit only

D.C. circuit only

A.C. and D.C. circuit

Neither A.C. nor D.C. circuits

219. When a magnet is moved with its north pole toward a coil placed in a closed circuit, then the nearest face of the coil

Shows south polarity

Shows north polarity

Shows no polarity

Shows sometimes north and sometimes south polarity

220. The equivalent capacitance in the circuit between A and B will be

1 μF

2 μF

3 μF

½ μF

221. A long copper pipe carries a current. Then the magnetic field is

Zero inside and finite outside

Finite inside and zero outside

Finite both inside and outside

Zero both inside and outside

222. When a charged particle enters in a uniform magnetic field, its kinetic energy

Remains constant

Increases

Decreases

Becomes zero

223. The defection in moving coil galvanometer falls from 50 division to 10 division, when a shunt of 12 Ω is applied, the resistance of galvanometer coil is

24 Ω

12 Ω

50 Ω

48 Ω

224. The Weber ampere per meter is equal to

Joule

Henry

Newton

Watt

225. A battery having emf 4V and internal resistance 0.5 Ω is connected with a resistance of 4.5 Ω, then the voltage at the terminals of battery is

4.5 V

4 V

0 V

2 V

Page 10 of 10

226. The angle which specifies the instantaneous value of the alternating voltage or current is called

Phase

Critical angle

Angle of incidence

All of these

227. The highest value reached by voltage or current in one cycle is called

Root mean square value

Peak value

Peak to peak value

Instantaneous value

228. 10⁶ electrons are moving through a wire per second, the current developed is

1.6 x 10¯¹⁹ A

1 A

1.6 x 10¯¹⁵ A

10⁶ A

229. In an A.C. circuit, the current lags behind the voltage by π/3. The components in the circuit are

R and L

L and C

R and C

Only R

230. The core of a transformer is laminated so that

The ratio of the voltage in the secondary to that in the primary may be increased

The weight of the transformer may be reduced

Energy losses due to eddy currents may be minimized

Rusting of the core may be prevented

231. If two bulbs one of 60 W and other of 100 W are connected in parallel, then which one of the following will flow more?

60 W bulb

100 W bulb

Both equally

None of these

232. The resistance of 20 cm long wire is 10Ω. When the length is changed to 40 cm. The new resistance is

10 Ω

20 Ω

30 Ω

40 Ω

233. The peak value of alternating voltage is given by

V = V₀ √2

V = V₀/√2

V = √2/V

1/√2V₀

234. The root mean square voltage for alternating current is

Vrms = √V₀²/2

Vrms = V₀/√2

Vrms = 0.707V₀

All of these

235. If a current is passed through a spring then the spring will

Expand

Compress

Remain same

None of these

236. Three resistors of resistance R each are combined in various ways. Which of the following cannot be obtained?

3R Ω

2R/4 Ω

R/3 Ω

2R/3 Ω

237. Which one of the following causes production of heat when current is set up in a wire?

Fall of electrons from higher orbits to lower orbits

Inter-atomic collisions

Inter-electron collisions

Collisions of conduction electrons with atoms

Total Questions:	50
Time Allowed:	20 Minutes
Total Marks:	50
How to Attempt Test:	Please choose the right Option in MCQ-type question.
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