Free Printable Single Phase AC circuits

1.

What is a passive component?

a)

Resistor

b)

Capacitor

c)

Inductor

d)

Transistor

2.

The use of inductor?

a)

Passive component that store food in a fridge when electric current flows through it.

b)

Passive component that store energy in a magnetic field when electric current flow through it

c)

Passive component that store electric charge in an AC circuit.

d)

Passive component that limit the current flow.

3.

What is period

a)

Time required for a sine wave to complete one full cycle.

b)

It is equal to frequency.

c)

Unit = second

d)

T = 1/f

4.

What is amplitude?

a)

V_pp or I_pp

b)

V_rms or I_rms

c)

V_p or I_p

d)

Positive or Negative maximum value of the sine wave

5.

What is root mean square, rms?

a)

Can be read using multimeters

b)

The main supply in our home is 240V. So this is rms value.

c)

V_rms = 0.707 × V_p

d)

Also known as Effective voltage.

6.

A heater is rated as 230 V, 10 kW. The value 230 V refers to

a)

average voltage

b)

r.m.s voltage

c)

peak voltage

7.

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 sam circuit

8.

If a sinusoidal wave has a frequency of 50 Hz with 30 A r.m.s current, which of the following equation represents the wave?

a)

42.42 sin 314.2t

b)

60 sin 25t

c)

30 sin 50t

d)

84.84 sin 25t

9.

In purely capacitor circuit

a)

Voltage lead current by 90 degree

b)

Voltage lag current by 90 degree

c)

Current lead voltage by 90 degree

d)

Current lead voltage by -90 degree

10.

Average power in single phase AC circuit is zero. This means circuit is

a)

series RLC circuit

b)

parallel RLC circuit

c)

pure inductive circuit

d)

pure resistance circuit

11.

if $v=V_{0_{\ }}Sin\ \left(314t+13^0\right)$ , the voltage in polar form will be

a)

$\frac{V}{\sqrt{2}}\angle13^0$

b)

$\frac{V_0}{\sqrt{2}}\angle13^0$

c)

$V_0\angle13^0$

d)

$v\angle13^0$

12.

For a single phase 25 Hz ac system, supply voltage is $100\angle25^0$ . the equivalent sinusoidal volatge is

a)

$v=141.4\sin\left(314t+25^0\right)$

b)

$v=100\sin\left(157t+25^0\right)$

c)

$v=141.4\sin\left(157t+25^0\right)$

d)

$v=100\sin\left(314t+25^0\right)$

13.

The power factor is defined as

a)

cosine of the phase difference between voltage and current

b)

ratio of resistance with impedance

c)

ratio of active power with apparent power

d)

All of above

14.

power factor is 0.95 lagging indicates

a)

Current lags to voltage by $\cos^{-1}\left(0.95\right)$

b)

Voltage lags to current by $\cos^{-1}\left(0.95\right)$

c)

any one may correct

d)

both are correct

15.

For a series R-L circuit having inductive reactance 3 ohm and resistance $\sqrt{3}$ . The power factor will be

a)

0.5

b)

1

c)

0

d)

$\sqrt{3}$

16.

1. Voltage in sinusoidal form is $v=230\sin\left(314t+46^0\right)$ . The value after converting into rectangular form is

a)

110.06+j115.41

b)

112.98+j116.99

c)

112.98-j116.99

d)

116.99+j112.98

17.

If 0.5 ohm resistance 10 mili Henry inductance and 1000 micro Farad are connected in series with 50 Hz single phase AC supply. The load power factor will be

a)

0.99

b)

0.999

c)

0.996

d)

0.991

18.

Active power is also named as,

a)

Real power

b)

True power

c)

kW power

d)

All of the above

e)

None of these

19.

power factor is defined as

a)

$\frac{impedance}{resis\tan ce\ }$

b)

$\frac{active\ power}{reactive\ power}$

c)

$\frac{kW}{kVA}$

d)

cosine of the angle of current

20.

$v=40\angle60^0\$ voltage is connected across series R and L. A current $i=10\angle30^0$ is flowing in the circuit. Assuming 50 Hz single phase AC supply, the value of R and L will be

a)

3.464 ohm and 6.37 mH

b)

3.56 ohm and 9.37 mH

c)

3.464 ohm and 6 mH

d)

3.464 ohm and 16.37 mH

21.

if apparent power is 100 kVA and real power is 60 kW. the reactive power will be

a)

80 kVAR

b)

40 kVAR

c)

160 kVAR

d)

80 kW

22.

√(-300)

a)

10i√3

b)

15√15

c)

-10√3

d)

2i√13

23.

Write an equation for the cosine signal with amplitude 3, period 2pi, phase shift of pi, and vertical shift of 5.

a)

y = 5cos(t - pi) + 3

b)

y = 3cos(t - pi) + 5

c)

y = 3cos(2t - pi) + 5

d)

y = 5cos(2t - pi) + 3

24.

Which equation?

a)

y= -cos(2t)

b)

y= cos(2t)

c)

y= (1/2)cos(t)

d)

y= (-1/2)cos(x)

25.

A sinusoidal voltage is expressed as $v=20\ \sin\ \left(314.16\ t\ +\frac{\pi}{3}\right)\ V.$ Its frequency and phase angle, respectively, are

a)

314.6 Hz, 60 $\degree$

b)

60 Hz, 60 $\degree$

c)

50Hz, 60 $\degree$

d)

50 Hz, -60 $\degree$

26.

A sinusoidal voltage varies from zero to maximum of 250V. the voltage at the instant of $60\degree$ of the cycle will be

a)

150V

b)

216.5V

c)

125V

d)

108.25V

27.

In an AC circuit , if $V=100\angle60\degree\ \&\ I=10\angle30\degree$ . What will be the real power?

a)

86W

b)

8.6W

c)

866W

d)

866 KW

28.

In an AC circuit , if $V=100\angle60\degree\ \&\ I=10\angle30\degree$ . What will be the reactive power?

a)

500 VAR

b)

5 VARW

c)

50 VARW

d)

500 KVAR

29.

IN a RL circuit, V_R=2V and V_L=3V. The magnitude of the total voltage is

a)

5V

b)

6V

c)

1V

d)

3.6V

30.

Given $v=200\sin377t\ and\ i=8\sin\left(377t-30\degree\right)$ for an AC circuit. What will be the power factor and True Power of the circuit?

a)

0.866 leading and 692.82W

b)

0.866 lagging and 692.82W

c)

0.866 leading and 800 W

d)

0.866 lagging and 800 W

Single Phase AC circuits

Total questions: 30

Worksheet time: 36mins

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