Free Printable ALTERNATING CURRENTS -2

1.

The r.m.s value of an alternating current is given by steady (D.C) current which when flowing through a given circuit for a given time produces

a)

the more heat than produced by A.C when flowing through the sam circuit

b)

the less heat than produced by A.C when flowing through the sam circuit

c)

the same heat than produced by A.C when flowing through the same circuit

2.

An inductor of inductance 22.0 mH is connected to an a.c. supply with frequency f. If the reactance of the inductor is 660 Ω, what is the value of f?

a)

1.45 $\times10^3\$ Hz

b)

3.00 $\times10^3\$ Hz

c)

4.77 $\times10^3\$ Hz

d)

7.16 $\times10^3\$ Hz

3.

The variation of voltage across an inductor with time t in an a.c. circuit is as shown in the graph. Which graphs shows the variation of the current I which flows through the inductor with time t?

a)

b)

c)

d)

4.

A pure inductor is connected to an a.c. source of frequency 100 Hz and the r.m.s. value of the voltage is 12 V. If the peak value of the current flowing through the inductor is 14 A, what is the inductance of the inductor?

a)

1.6 mH

b)

1.9 mH

c)

30 mH

d)

39 mH

5.

A pure inductor of inductance 15 H is connected to an a.c.s source of frequency 100 Hz. If the r.m.s. value of the voltage is 12 V, what is the maximum instantaneous output power?

a)

1.3 $\times10^{-3}W$

b)

1.5 $\times10^{-2}W$

c)

0 W

d)

1.5 W

6.

A pure capacitor of capacitance C is connected to an a.c. supply of peak voltage V₀. Which pair of expressions below are for the voltage and current in the circuit?

a)

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

b)

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

c)

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

d)

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

7.

A pure capacitor is connected to an a.c. supply of frequency 50 Hz and r.m.s. voltage 6.0 V. If the r.m.s. value of the current in the circuit is 30 mA, what is the capacitance of the capacitor?

a)

13 $\mu$ F

b)

14 $\mu$ F

c)

15 $\mu$ F

d)

16 $\mu$ F

8.

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

9.

An A.C source is connected to a resistive circuit. Which of the following is true ?

a)

Current leads the voltage and both are in same phase

b)

Current lags behind the voltage and both are in same phase

c)

Current and voltage are in same phase

d)

Any of the above may be true depending upon the value of resistance

10.

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.

11.

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 CURRENTS -2

Total questions: 11

Worksheet time: 55mins

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