Free Printable Alternating current

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.

The formula for inductive reactance is

a)

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

b)

$\omega C$

c)

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

d)

$\omega L$

6.

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)

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

7.

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

8.

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

9.

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

a)

Infinite

b)

100

c)

0

d)

1

10.

An electrical element X when connected to an alternating voltage source has current through it leading the voltage by 2radian. Identify X

a)

Capacitor

b)

Resistor

c)

Inductor

d)

Series LR circuit

11.

If an electric bulb is connected to an AC source, which of the following statement is true about the phase difference between the voltage across the bulb and current flowing in it?

a)

In phase.

b)

Not in phase.

c)

The voltage is leading the current.

d)

The current is leading the voltage.

12.

Which one of the below AC parameters show the effective Dc value?

a)

Peak Value

b)

RMS value

c)

Peak to peak value

d)

Frequency

Alternating current

Total questions: 12

Worksheet time: 6mins

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