Alternating Current

Question 1

When DC is applied to a circuit containing a capacitor in series with a lamp, the lamp will

Answer 1

Light only during the charging period

Question 2

When AC is applied to a circuit containing a capacitor in series with a lamp, the lamp will

Answer 2

Light

Question 3

When DC is applied to a circuit containing no resistance and an inductor in series with a lamp, the lamp will

Answer 3

Light

Question 4

When AC is applied to a circuit containing no resistance and an inductor in series with the lamp, the lamp will

Answer 4

Light dim for continuous period

Question 5

Slip rings are used on

Answer 5

AC generators

Question 6

A commuter is used in

Answer 6

DC generators

Question 7

An alternator produces which type of waveform

Answer 7

Sinussoidal

Question 8

How do u find the peak voltage if the RMS (root mean square) is 200V

Answer 8

200/0.707=282V

Question 9

Why is a commuter used in a DC generator

Answer 9

To provide DC output

Question 10

With in the ESB generation stations, 3 phase generators produce voltage at

Answer 10

10,000V AC 50 Hz

Question 11

An alternating current is best defined by a graph which will indicate the

Answer 11

Sinussoidal waveform

Question 12

The number of cycles of an alternating system traced out each second is called

Answer 12

Frequency

Question 13

The periodic time of a AC system is the

Answer 13

Time taken to complete one cycle

Question 14

The frequency of an AC system is measured in

Answer 14

Hertz

Question 15

What is the name of the rings that rotate in a AC generator

Answer 15

Slip rings

Question 16

What is attached to to slip rings in a AC generator to make contact with the coil.

Answer 16

Carbon brush’s

Question 17

In AC generators what is one revolution of a coil referred to as

Answer 17

One cycle

Question 18

How is the frequency of a supply calculated

Answer 18

F=1/T
F=frequency
T=time (periodic time, one complete cycle)

Question 19

What it the highest point in a AC wave form called

Answer 19

Peak or maximum value

Question 20

What is the RMS (root mean value) also know as

Answer 20

Effective value (0.707)

Question 21

What is the average value also know as

Answer 21

Mean value (0.637)

Question 22

How do you find the Peak (max)value

Answer 22

RMS(effective) value

      0. 707

Question 23

How do you find the average (mean) value

Answer 23

Peak value X 0.637

Question 24

How do you find RMS (effective) value

Answer 24

Peak(max) value X 0.707

Question 25

How do you find the peak(max) value

Answer 25

Average (mean) value

            0. 637

Question 26

The power factor of a purely resistive component connected to a AC supply is ?

Answer 26

Unity

Question 27

What type of a component has a leading power factor?

Answer 27

A capacitor

Question 28

In AC the current in a purely capacitive circuit

Answer 28

Lead the voltage by 90 degrees

Question 29

In AC the current in a purely inductive circuit

Answer 29

Lags the voltage by 90 degrees

Question 30

What effect limits the current flow in a pure inductive circuit in AC ?

Answer 30

Inductive reactance