Question 4
- (i) Define rectification.
(ii)Fig. 5 is a fragment of a block diagram of a power supply unit.
Using Fig. 5, complete Table 1.
Table 1
|
Name of block |
Function |
X |
|
|
Y |
|
|
- State the difference between a half-wave recitifer and a bridge rectifier in relation to:
- number of diodes used;
- frequency of the output signal.
- Fig. 6 is a series RLC circuit at resonance.
Calculate the resonance frequency.
Observation
The expected answers were:
(a) (i) Rectification is the process of converting alternating current (a.c.) to direct current (d.c.).
(ii) Table 1
|
Name of block |
Function of block |
X |
Transformer |
|
Y |
Filter |
|
(b) Differences between half-wave rectifier and bridge rectifier
(i) half-wave rectifier uses one diode and bridge rectifier uses four diodes
(ii) frequency of the output signal is the same as input signal in half-wave rectifier while the
frequency is twice the input signal in bridge rectifierOR fo = 2fin
(c) 
Many candidates did not respond well to this question.