Alternating Current Test

Result

Alternating Current Test - 12

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Weekly Quiz Competition

Question 1
4 / -1

The power factor of an AC circuit having resistance R and inductance L (connected in series) and an angular velocity ω is

A
R/ωL

B
R/(R² + ω² L²)^1/2

C
ωL/R

D
R/(R² – ω² L²)^1/2

Solution
Question 2
4 / -1

An installation consisting of an electric motor driving a water pump left 75 L of water per sec of a height of 4.7 m. If the motor consumes a power of 5 kW, then the efficiency of the installation is

A
39%

B
69%

C
93%

D
96%

Solution
Question 3
4 / -1

An ideal transformer has 500 and 5000 turn in primary and secondary windings respectively. If the primary voltage is connected to a 6 V battery, then the secondary voltage is

A
zero

B
60 V

C
0.6 V

D
6.0 V
Question 4
4 / -1

A resistor and a capacitor are connected in series with an AC source. If the potential drop across the capacitor is 5 V, and that across resistor is 12 V, then applied voltage is

A
13 V

B
17 V

C
5 V

D
12 V

Solution
Question 5
4 / -1

An ideal coil of 10 H is connected in series with a resistance of 5 Ω and a battery of 5 V. 2 s after the connection is made, the current flowing (in ampere) in the circuit is

A
(1 – e)

B
e

C
e^-1

D
(1 – e^-1)

Solution
Question 6
4 / -1

A coil of inductance 300 mH and resistance 2 Ω is connected to a source of voltage 2V. The current reaches half of its steady state value in

A
0.05 s

B
0.1 s

C
0.15 s

D
0.3 s

Solution
Question 7
4 / -1

A 4µF capacitor, a resistance of 2.5 m Ωis in series with 12 V battery. Find the time after which the potential difference across the capacitor is 3 times the potential difference across the resistor. (given, ln (2) = 0.693)

A
13.86 s

B
6.93 s

C
7 s

D
14 s

Solution
Question 8
4 / -1

A coil is wound on an iron core and looped back on itself so that core has two sets of closely wound coils carrying currents in opposite directions. The self-inductance is

A
zero

B
2L

C
2L + M

D
2L+ 2M

Solution
Question 9
4 / -1

A movable wire is moved to the right causing an anticlock-wise induced current Fig. The direction of magnetic induction in the region P points

A
to the right

B
to the left

C
up the paper

D
down into the paper
Question 10
4 / -1

In the circuit shown in Fig, the bulb B will become suddenly bright when

A
Contact is made or broken

B
Contact is made

C
Contact is broken

D
Won’t become bright at all