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Basic AC Theory

Total questions: 11

Worksheet time: 8mins

Name
Class
Date
1.
In a circuit consisting of a resistor connected to an AC supply, the current
a)
leads the voltage
b)
lags the voltage
c)
is in phase with the voltage
d)
depends on the source of voltage
2.
A capacitor is connected to an AC voltage. As the frequency of the voltage increases, the capacitive reactance
a)
increases
b)
decreases
c)
remains the same
d)
depends on the direction of current
3.

The frequency of an alternating electrical system is measured in

a)

cycles

b)

volts

c)

hertz

d)

seconds

4.

A phasor is

a)

part of a three-phase system

b)

a method of representing a sinusoidally varying system

c)

the angle between alternating current and voltage

d)

always measured in radians

5.

The effect which limits current flow in a pure inductor connected to an

alternating-voltage supply is called the

a)

induced EMF

b)

inductive reactance

c)

capacitive reactance

d)

resistance

6.

If a supply at 230V, 50Hz is connected to a 420mH inductor, the current

flow will be

a)

1.74 A

b)

0.57 A

c)

11.4 A

d)

31.6 μA

7.

If a sinusoidal voltage is applied to a pure capacitor

a)

the average current flow will be zero

b)

the current will lead the voltage by 900

c)

the current will lag the voltage by 900

d)

current and voltage will be in phase

8.

An alternating supply of 12V at 1kHz is connected to a capacitor, and

the current is found to be 15mA. The capacitance of the capacitor is

a)

800 Ω

b)

625 nF

c)

50.3 μF

d)

198 nF

9.

The opposition to current flow in an AC resistive circuit is called:

a)

resistance

b)

inductance

c)

reactance

d)

impedance

10.

The opposition to current flow in an AC capacitive or inductive current is

called:

a)

resistance

b)

inductance

c)

reactance

d)

impedance

11.

A straight line having definite length and direction that represents to scale a

quantity such as current voltage or impedance is called:

a)

a series AC circuit

b)

capacitive reactance

c)

a phasor, as in a phasor diagram

d)

the impedance triangle