Current Electricity MCQs

Question 1

A typical use of an LDR is:

Accepted Answer

automatic street lights

Answer

a fuse

Answer

a loudspeaker

Answer

a heating element

Question 2

A wire has resistivity 1.7 10^-8 Ω m, length 10 m and cross-section 1 10^-6 m^2. Its resistance is:

Accepted Answer

0.17 Ω

Answer

0.34 Ω

Answer

1.7 Ω

Answer

0.017 Ω

Question 3

The drift velocity of electrons in a typical wire is:

Accepted Answer

less than a millimetre per second

Answer

about 1 km/s

Answer

about 300 m/s

Answer

about the speed of light

Question 4

A device draws 0.5 A from a 230 V supply. Its power is:

Accepted Answer

115 W

Answer

460 W

Answer

57.5 W

Answer

230 W

Question 5

The reading of a galvanometer at the null point is independent of its resistance because:

Accepted Answer

no current flows through it

Answer

the current is very large

Answer

it has zero resistance

Answer

it is in parallel

Question 6

In terms of energy, the 'lost volts' inside a cell represent:

Accepted Answer

energy wasted as heat in the internal resistance

Answer

energy gained by the cell

Answer

energy given to the lamp

Answer

energy stored in the wires

Question 7

A source of e.m.f. 12 V drives 2 A for 30 s. The energy it supplies is:

Accepted Answer

720 J

Answer

1440 J

Answer

24 J

Answer

360 J

Question 8

When applying Kirchhoff's second law to a loop, you must:

Accepted Answer

include every e.m.f. and IR term around the loop with correct signs

Answer

add all currents

Answer

ignore resistors

Answer

include only the batteries

Question 9

Energy wasted inside a battery due to its internal resistance appears as:

Accepted Answer

heat in the battery

Answer

light

Answer

extra e.m.f.

Answer

sound

Question 10

Three identical 1.5 V cells in parallel give an e.m.f. of:

Accepted Answer

1.5 V

Answer

0.5 V

Answer

3.0 V

Answer

4.5 V

Question 11

A high resistance is often placed in series with the galvanometer at first to:

Accepted Answer

protect it while finding the approximate balance point

Answer

make it read zero

Answer

reverse the current

Answer

increase its sensitivity

Question 12

Which graph shows the behaviour of an LDR?

Accepted Answer

resistance falling as light intensity rises

Answer

resistance rising with light

Answer

resistance rising with temperature

Answer

a horizontal line

Question 13

The SI unit of resistivity is:

Accepted Answer

Ω m

Answer

Ω

Answer

Ω m^2

Answer

Ω/m

Question 14

A current of 2 A flows in a wire with n = 8.5 10^28 m^-3 and area 1 10^-6 m^2. The drift velocity of the electrons is:

Accepted Answer

1.47 10^-4 m/s

Answer

1.47 10^-5 m/s

Answer

0.00147 m/s

Answer

2.94 10^-4 m/s

Question 15

A 46 Ω resistor is connected to 230 V. The power is:

Accepted Answer

1150 W

Answer

5 W

Answer

2300 W

Answer

10,600 W

Question 16

Three 1.5 V cells in series have a total e.m.f. of:

Accepted Answer

4.5 V

Answer

1.5 V

Answer

3.0 V

Answer

0.5 V

Question 17

For a load much larger than the internal resistance, the terminal p.d. is:

Accepted Answer

almost equal to the e.m.f.

Answer

twice the e.m.f.

Answer

almost zero

Answer

half the e.m.f.

Question 18

Kirchhoff's first law is a consequence of the conservation of:

Accepted Answer

charge

Answer

mass

Answer

energy

Answer

momentum

Question 19

A coulomb of charge going once round a circuit with a 6 V battery loses in the components a total energy of:

Accepted Answer

6 J

Answer

12 J

Answer

3 J

Answer

0 J

Question 20

Resistors of 1.5 Ω, 2.5 Ω, 6 Ω are connected in series. The combined resistance is:

Accepted Answer

10 Ω

Answer

5 Ω

Answer

20 Ω

Answer

100 Ω

Question 21

A charge of 40 C moves through a p.d. of 1.5 V. The energy transferred is:

Accepted Answer

60 J

Answer

120 J

Answer

30 J

Answer

0.0375 J

Question 22

A potential divider works by:

Accepted Answer

sharing the supply p.d. between resistors in proportion to their resistances

Answer

storing charge

Answer

changing the e.m.f.

Answer

adding current

Question 23

Kirchhoff's second law states that around any closed loop:

Accepted Answer

the sum of the e.m.f.s equals the sum of the p.d.s (IR terms)

Answer

the resistance is zero

Answer

the current is the same

Answer

the sum of the currents is zero

Question 24

In the loop above, the p.d. across the 4 Ω resistor is:

Accepted Answer

8 V

Answer

2 V

Answer

12 V

Answer

4 V

Question 25

Three identical lamps in parallel draw 0.6 A in total. Each lamp carries:

Accepted Answer

0.2 A

Answer

1.8 A

Answer

0.6 A

Answer

0.3 A

Current Electricity MCQs — Physics (page 6)

126. A typical use of an LDR is:

127. A wire has resistivity 1.7 10^-8 Ω m, length 10 m and cross-section 1 10^-6 m^2. Its resistance is:

128. The drift velocity of electrons in a typical wire is:

129. A device draws 0.5 A from a 230 V supply. Its power is:

130. The reading of a galvanometer at the null point is independent of its resistance because:

131. In terms of energy, the 'lost volts' inside a cell represent:

132. A source of e.m.f. 12 V drives 2 A for 30 s. The energy it supplies is:

133. When applying Kirchhoff's second law to a loop, you must:

134. Energy wasted inside a battery due to its internal resistance appears as:

135. Three identical 1.5 V cells in parallel give an e.m.f. of:

136. A high resistance is often placed in series with the galvanometer at first to:

137. Which graph shows the behaviour of an LDR?

138. The SI unit of resistivity is:

139. A current of 2 A flows in a wire with n = 8.5 10^28 m^-3 and area 1 10^-6 m^2. The drift velocity of the electrons is:

140. A 46 Ω resistor is connected to 230 V. The power is:

141. Three 1.5 V cells in series have a total e.m.f. of:

142. For a load much larger than the internal resistance, the terminal p.d. is:

143. Kirchhoff's first law is a consequence of the conservation of:

144. A coulomb of charge going once round a circuit with a 6 V battery loses in the components a total energy of:

145. Resistors of 1.5 Ω, 2.5 Ω, 6 Ω are connected in series. The combined resistance is:

146. A charge of 40 C moves through a p.d. of 1.5 V. The energy transferred is:

147. A potential divider works by:

148. Kirchhoff's second law states that around any closed loop:

149. In the loop above, the p.d. across the 4 Ω resistor is:

150. Three identical lamps in parallel draw 0.6 A in total. Each lamp carries:

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