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.

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.

All of the following have the same units except:

a)

inductance.

b)

capacitive reactance.

c)

impedance.

d)

resistance.

17.

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

18.

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.

19.

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°

20.

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

a)

b)

c)

d)

21.

Quantity of charge can be measured in

a)

time (s)

b)

Ampere (A)

c)

coulombs (C)

d)

Joule (J)

22.

The formula for inductive reactance is

a)

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

b)

$\omega C$

c)

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

d)

$\omega L$

23.

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)

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

24.

What happens at resonance?

a)

Current is maximum

b)

Impedance is maximum

c)

Resistance is maximum

d)

Power factor is maximum

25.

The power factor of an RLC circuit is defined as cos ∅ = R/Z, but the phase angle can also be calculated from ________.

a)

sin ∅ = (XL - XC)/Z

b)

sin ∅ = (XL - XC)/RZ

c)

sin ∅ = Z/(XL - XC)

d)

sin ∅ = RZ/(XL - XC)

26.

What is alternating current

a)

the process of inducing an emf (voltage) with a change in magnetic flux

b)

Electric currents whose direction and magnitude change periodically depending on time are called alternating current

c)

Steady current which delivers the same average power as the a.c. to a resistive load.

d)

Making a rectified current more steady (or smooth) by placing a capacitor in parallel with the resistor

27.

What does AC smoothing mean?

a)

the process of inducing an emf (voltage) with a change in magnetic flux

b)

Electric currents whose direction and magnitude change periodically depending on time are called alternating current

c)

Steady current which delivers the same average power as the a.c. to a resistive load.

d)

Making a rectified current more steady (or smooth) by placing a capacitor in parallel with the resistor

28.

Defines of the effective value of alternating current

a)

The process of inducing an emf (voltage) with a change in magnetic flux

b)

Electric currents whose direction and magnitude change periodically depending on time are called alternating current

c)

Steady current which delivers the same average power as the a.c. to a resistive load.

d)

Making a rectified current more steady (or smooth) by placing a capacitor in parallel with the resistor

29.

Electromagnetic Induction is ...

a)

The process of inducing an emf (voltage) with a change in magnetic flux

b)

Electric currents whose direction and magnitude change periodically depending on time are called alternating current

c)

Steady current which delivers the same average power as the a.c. to a resistive load.

d)

Making a rectified current more steady (or smooth) by placing a capacitor in parallel with the resistor

30.

If the Y-sensitivity and time-base for the trace shown in Figure are 5 V/cm and 20 ms/cm, what are the amplitude, period and frequency of the signal to Y-input?

a)

3.5 V, 80 ms, 50 Hz

b)

20 V, 40 ms, 50 Hz

c)

17.5 V, 80 ms, 12.5 Hz

d)

22.5 V, 12.5 ms, 55 Hz

31.

Find the inductive reactance of the circuit shown in the figure

a)

100Ω

b)

6,28Ω

c)

3,14Ω

d)

5,22Ω

32.

A series RLC circuit has a resistance of 10.0 Ω and a impedance of 50.0 Ω. If the rms voltage applied to the circuit is 10 V, what average power?

a)

0.4W

b)

4W

c)

5W

d)

50W

33.

A series RLC circuit has a resistance of 10.0 Ω and a impedance of 50.0 Ω. If the rms voltage applied to the circuit is 10 V, what rms current?

a)

0.5A

b)

1A

c)

2A

d)

0.2A

34.

What is the phase difference between voltage and current in an alternating current circuit if the inductive reactance is 26 Ohm, the capasitive reactance is 20 Ohm and the active resistance is 8 Ohm?

a)

53⁰

b)

25⁰

c)

120⁰

d)

67⁰

35.

What is not the reason for the loss of power in the transformer

a)

Heat loss due to the resistance of the coils

b)

Leakage of magnetic field lines between the primary and secondary coils

c)

Heat loss due to eddy currents induced in the iron core

d)

Heat loss due to radiation of electromagnetic waves

e)

Heat loss due to repeated magnetization and demagnetization of the core

36.

A pure resistor is connected to an a.c. source where its current is given by I=5.0 sin 628t. Which of the following statements is not true about the circuit?

a)

The peak value of current flowing through the resistor is 5.0 A

b)

The root mean square current flowing through the resistor is 3.5 A

c)

The frequency of the current flowing through across the resistor is 120 Hz

d)

The equivalent direct current which gives the same average heating power in the resistor is 3.5 A

37.

Which of the following statements is not true about the above circuit?

a)

The instantaneous current in the circuit is I=I0 sin $\omega t$

b)

The peak value of the alternating current is $\frac{V_0}{R}$

c)

The impedance of the circuit is $\omega R$

d)

The hot-wire ammeter in the circuit can also be used to measure the direct current

38.

a)

A

b)

B

c)

C

d)

D

39.

Find the ratio of $\frac{mean\ power\ dissipated\ through\ R\ in\ \left(a\right)}{power\ dissipated\ through\ R\ in\ \left(b\right)}$

a)

2

b)

$\frac{1}{2}$

c)

4

d)

$\frac{1}{4}$

40.

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)

3.00undefined Hz

c)

4.77undefined Hz

d)

7.16undefined Hz

41.

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)

42.

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

43.

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

44.

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)

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

45.

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)

14undefinedF

c)

15undefinedF

d)

16undefinedF

46.

An alternating current I which flows through a capacitor of capacitance 2 μF is given by $I=5\ \sin\ \left(100t\right)$ . If $I$ is in ampere and t is seconds, what is the mean power generated in the capacitor?

a)

0 W

b)

5 W

c)

7 W

d)

10 W

47.

A sinusoidal a.c. source of r.m.s. voltage 25 V as shown in the diagram. If the potential difference across the resistor R has an r.m.s. value of 10 V, what is the potential difference across the capacitor?

a)

10 V

b)

15 V

c)

23 V

d)

25 V

48.

A pure inductor of inductance 0.20 H and a resistor of resistance 200 $\Omega$ are connected in series to an a.c. source of voltage V=300 sin 120t. Calculate the r.m.s. value of current in the circuit.

a)

1.1 A

b)

8.8 A

c)

9.3 A

d)

10 A

49.

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

a)

b)

c)

d)

50.

a)

A

b)

B

c)

C

d)

D

51.

The reactance Xc of the capacitor and the resistance R are shown in the phasor diagram. Which of the following statements describes Z and $\phi$ correctly?

a)

Z is the impedance of the combined R and $X_c$
$\phi$ is the phase angle where current leads the voltage

b)

Z is the impedance of the combined R and $X_c$
$\phi$ is the phase angle where voltage leads the current

c)

Z is the reactance of the resistor
$\phi$ is the phase angle where R leads Z.

d)

Z is the impedance of the combined R and $X_c$
$\phi$ is the phase angle where Z leads R

52.

In an RC, RL or RCL circuit, the total opposition to alternating current is called as

a)

Reactant

b)

Impedence

c)

Phase angle

d)

Resistance

53.

Based on the phasor diagram of RL circuit. The rms supply voltage V (or total voltage) of the circuit is given by

a)

The sum of all voltage in the circuit.

b)

The sum of the squares of voltage across R and L

c)

The square root of the sum of the squares of the voltage across R and L,

d)

The square root of the sum of all voltage in the circuit

54.

At resonance frequency...

a)

Impedence is minimum, rms current flow is maximum

b)

Impedence is maximum, rms current flow is minimum

c)

Impedene is zero, rms current flow is maximum

d)

Impedence is increasing, rms current flow is decreasing

55.

Choose the wrong statement about the power of an ac circuit

a)

There are no power dissipated in capacitor and inductor

b)

power is only dissipated in resistor

c)

the ratio of real power to apparent power is called the power factor

d)

At resonance, power factor is equal to real power

56.

Instantaneous power is defined as

a)

the product of instantaneous current and voltage

b)

the product of rms current and voltage

c)

the product of peak current and voltage

d)

specific power

57.

An alternating current I in amperes varies with time t in seconds as I=2 sin 300πt. The rms value of the current in A and the frequency f in Hz are

a)

Irms=1.4 A, f=100 Hz

b)

Irms=1.4 A, f=150 Hz

c)

Irms=2 A, f=250 Hz

d)

Irms=2 A, f=300 Hz

58.

All of the following have the same units except:

a)

inductance.

b)

capacitive reactance.

c)

impedance.

d)

resistance.

59.

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

60.

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.

61.

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°

62.

The formula for inductive reactance is

a)

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

b)

$\omega C$

c)

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

d)

$\omega L$

63.

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)

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

64.

What happens at resonance?

a)

Current is maximum

b)

Impedance is maximum

c)

Resistance is maximum

d)

Power factor is maximum

65.

A Capacitor blocks

a)

Only a.c.

b)

Only d.c.

c)

Both ac and dc

d)

None of these

66.

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

a)

Infinite

b)

100

c)

0

d)

1

67.

Consider an RLC circuit that is driven by an AC applied voltage. At resonance,

a)

the peak voltage across the capacitor is greater than the peak voltage across the inductor.

b)

the peak voltage across the inductor is greater than the peak voltage across the capacitor.

c)

the current is in phase with the driving voltage.

d)

the peak voltage across the resistor is equal to the peak voltage across the inductor.

68.

A capacitor 120 µF is connected to an AC source of 6 V with frequency 100 Hz. If the frequency is increased to 200 Hz, the reactance of the capacitor will be

a)

half the original value.

b)

same as the original value.

c)

two times the original value.

d)

the reciprocal of the original value.

69.

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.

70.

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.

71.

A pure capacitor 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

72.

A sine wave has a peak value of 354 V, What is the RMS value?

a)

250 V

b)

500 V

c)

354 V

d)

200V

73.

All of the following have the same units except:

a)

inductance.

b)

capacitive reactance.

c)

impedance.

d)

resistance.

74.

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

75.

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.

76.

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.

77.

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.

78.

A pure capacitor 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

79.

A capacitor 120 µF is connected to an AC source of 6 V with frequency 100 Hz. If the frequency is increased to 200 Hz, the reactance of the capacitor will be

a)

half the original value.

b)

same as the original value.

c)

two times the original value.

d)

the reciprocal of the original value.

80.

A sine wave has a peak value of 354 V, What is the RMS value?

a)

250 V

b)

500 V

c)

354 V

d)

200V

81.

The sum of resistance and reactance is referred to as ________.

a)

geometric resistance

b)

conductance

c)

impedance

d)

susceptance

82.

The opposition to AC current flow presented by capacitors and inductors is called:

a)

Resistance

b)

Reactance

c)

Impedance

d)

Reluctance

83.

The formula for inductive reactance is _____.

a)

XL = 1 ÷ 2πfL

b)

XL = 2 ÷ πfL

c)

XL = 2π ÷ fL

d)

XL = 2πfL

84.

What is alternating current

a)

the process of inducing an emf (voltage) with a change in magnetic flux

b)

Electric currents whose direction and magnitude change periodically depending on time are called alternating current

c)

Steady current which delivers the same average power as the a.c. to a resistive load.

d)

Making a rectified current more steady (or smooth) by placing a capacitor in parallel with the resistor

85.

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

86.

An alternating voltage is described by $V=240\sin400t$ , where $V$ is in volts. What is the r.m.s. voltage?

a)

240 V

b)

250 V

c)

170 V

d)

340 V

87.

The electricity in our house is

a)

AC

b)

DC

c)

BC

d)

AD

88.

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

89.

The unit of frequency is

a)

Cycle

b)

Cycle-second

c)

Hertz/second

d)

hertz

90.

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

a)

Zero

b)

One

c)

Eleven

d)

Infinity

91.

What is the duration of one cycle known as _________

a)

Waveform

b)

Peak value

c)

Instantaneous value

d)

Period

92.

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

a)

Waveform

b)

Instantaneous value

c)

Cycle

d)

Period

93.

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

a)

Peak value

b)

Peak to peak value

c)

Cycle

d)

Period

94.

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

95.

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

96.

A sine wave has a peak value of 354 V, What is the RMS value?

a)

250 V

b)

500 V

c)

354 V

d)

200V

97.

What is the Peak voltage of the signal shown on the multimeter?

a)

1000 V

b)

1414 V

c)

1500 V

d)

707 V

98.

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

99.

The period of a wave is

a)

the same as frequency

b)

time required to complete one cycle

c)

expressed in amperes

d)

none of the above

100.

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

101.

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

102.

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

103.

The type of current where charges shake back and forth in a circuit

a)

Alternating Current

b)

Direct Current

c)

Voltage

d)

Switchback Current

104.

AC stands for ___.

a)

Alternating Current

b)

Attraction Connections

105.

Current that is used by most household appliances

a)

AC

b)

DC

c)

BC

d)

AC/DC

106.

Current from a battery is

a)

AC

b)

DC

c)

BC

d)

AC/DC

107.

The RMS voltage of a sine wave is the same as the average voltage:

a)

True

b)

False

108.

RMS voltage of a sine wave is the same as:

a)

Effective voltage

b)

Average voltage

c)

Digital equivalent

d)

I can't think of another wrong answer

109.

To find the equivalent energy (power) of a 12 volt battery, which of the following has an EFFECTIVE voltage of 12?

a)

24 volts Vpp

b)

34 Vpp

c)

34 Vp

d)

I have no idea

110.

The amount of time for one complete cycle is called?

a)

Frequency

b)

Period

111.

Frequency is 1/period and period is 1/frequency? True or false?

a)

YEA baby

b)

Not until i meet you

c)

Only when the moon is full

112.

Diagrams of sine waves show two axis. The vertical axis is????

a)

Voltage or amplitude

b)

Time as in period or frequency

c)

Resistance to flow

d)

Tiang bendera sekolah awak

113.

To find the peak voltage of a waveform you:

a)

Divide Peak to peak by two

b)

Multiply Peak to Peak by 2

c)

Divide peak by .707

alternating current

Total questions: 113

Worksheet time: 59mins

Similar Resources on Wayground