Alternating Currents

Question 1

Define period in a.c.

Answer 1

The time taken for one complete a.c. cycle.

Question 2

Define peak value for current/voltage.

Answer 2

The maximum value for the current/voltage in a cyle

Question 3

What is the mean power for a sinusoidal alternating current?

Answer 3

Half the maximum power.

Question 4

What is the r.m.s value of an a.c current.

Answer 4

The r.m.s (root mean square) value for the alternating current or voltage is that value of the direct current or voltage that would dissipate the same power.

Question 5

Define rectification

Answer 5

The process of converting alternating current (a.c.) into direct current (d.c.)

Question 6

How does half-wave rectification work?

Answer 6

Using a single diode

Question 7

How does full-wave rectification work.

Answer 7

Using 4 diodes. Also know as a bridge rectifier circuit.

Question 8

What is the purpose of smoothing

Answer 8

To reduce the flcuctuations in the unidirectional output of a rectifier.

Question 9

How doe smoothing work?

Answer 9

A capacitor is connectedaccross the rectifier. The capacitor charges up on the rising part of the half-cycle, then discharges as the output voltage falls.

Question 10

Effect of the time constant on the ripple when smootihng.

Answer 10

A smaller value for the time constant will increase the ripple. LArger time constant will produce a smaller ripple.