Free Printable Alternating current class 12th physics

1.

All of the following have the same units except:

a)

inductance.

b)

capacitive reactance.

c)

impedance.

d)

resistance.

2.

A resistor is connected to an AC power supply. On this circuit, the current

a)

leads the voltage by 90°.

b)

lags the voltage by 90°.

c)

is in phase with the voltage.

d)

none of the given answers

3.

A pure inductor is connected to an AC power supply. In this circuit, the current

a)

leads the voltage by 90°.

b)

lags the voltage by 90°.

c)

is in phase with the voltage.

d)

none of the given answers.

4.

If the frequency of the AC voltage across an inductor is doubled, the inductive reactance of that inductor

a)

increases to 4 times its original value.

b)

increases to twice its original value.

c)

decreases to one-half its original value.

d)

decreases to one-fourth its original value.

5.

What is the phase angle between the voltages of the inductor and capacitor in a RLC series circuit?

a)

zero

b)

90°

c)

180°

d)

270°

6.

Which of the following diagrams is the correct phasor diagram for V_R,V_Land V?

a)

b)

c)

d)

7.

Quantity of charge can be measured in

a)

time (s)

b)

Ampere (A)

c)

coulombs (C)

d)

Joule (J)

8.

The function of a generator is to change ____.

a)

mechanical energy to electrical energy

b)

electrical energy to mechanical energy

c)

electrical energy to chemical energy

d)

chemical energy to electrical energy

9.

The formula for inductive reactance is

a)

$\frac{1}{\omega L}$

b)

$\omega C$

c)

$\frac{1}{\omega C}$

d)

$\omega L$

10.

The equations for alternating emf and alternating current in a circuit containing capacitor are

a)

$V\ =\ V_0\ \sin\ \omega t,\ I\ =\ I_0\ \sin\left(\omega t-\frac{\pi}{2}\right)$

b)

$V=V_0\ \sin\ \omega t\ ,\ I\ =\ I_0\ \sin\left(\omega t\ +\frac{\pi}{2}\right)$

c)

$V\ =\ V_0\ \sin\omega t,\ I\ =I_0\ \sin\ \omega t$

d)

$V\ =\ V_0\ \sin\left(\omega t\ +\frac{\pi}{2}\right),\ I\ =\ I_0\ \sin\ \omega t$

11.

What happens at resonance?

a)

Current is maximum

b)

Impedance is maximum

c)

Resistance is maximum

d)

Power factor is maximum

12.

A Capacitor blocks

a)

Only a.c.

b)

Only d.c.

c)

Both ac and dc

d)

None of these

13.

The instantaneous current in an ac circuit is i=2.0 sin314t, what is its frequency?

a)

100 Hz

b)

60 Hz

c)

50 Hz

d)

2π

14.

The instantaneous current in an ac circuit is i=2.0 sin314t, what is rms value of the current.

a)

1.414 A

b)

2.828A

c)

1 A

d)

2 A

15.

Average power dissipated in an ideal inductor in a.c. circuit is:

a)

Infinite

b)

100

c)

0

d)

1

16.

Alternating voltage (V) is represented by the equation

a)

V(t) = Vm eωt

b)

V(t) = Vm sin ωt

c)

V(t) = Vm cot ωt

d)

V(t) = Vm tan ωt

17.

The unit of frequency is

a)

Cycle

b)

Cycle-second

c)

Hertz/second

d)

hertz

18.

A vector quantity has

a)

Only magnitude

b)

Only direction

c)

Both (a) and (b)

d)

none of these

19.

The number of instantaneous values between zero and the peak value is

a)

Zero

b)

One

c)

Eleven

d)

Infinity

20.

The most common waveforms of ac is

a)

square wave

b)

triangular wave

c)

complex wave

d)

sine wave

21.

The variation of a quantity such as voltage or current shown on a graph is known as ___________

a)

Waveform

b)

Peak value

c)

Instantaneous value

d)

Period

22.

What is the duration of one cycle known as _________

a)

Waveform

b)

Peak value

c)

Instantaneous value

d)

Period

23.

The repetition of a variable quantity, recurring at equal intervals, is known as ___________

a)

Waveform

b)

Instantaneous value

c)

Cycle

d)

Period

24.

The value of a given waveform at any instant time is termed as ___________

a)

Waveform

b)

Instantaneous value

c)

Cycle

d)

Period

25.

The maximum instantaneous value measured from zero value is known as?

a)

Peak value

b)

Peak to peak value

c)

Cycle

d)

Period

Alternating current class 12th physics

Total questions: 25

Worksheet time: 13mins

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