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The voltage at point A
does the opposite of
that at point B.
When A is increasing in
a positive direction, B
is increasing in a
negative direction.
It is rather like the
two ends of a see-saw.
During the first half
cycle of the waveform
shown on the left, A is
positive and B is
negative.
The diode is forward
biased and current flows
around the circuit
formed by the diode, the
transformer winding and
the load.
Since the current
through the load, and
the voltage across the
load are in the same
proportions, then the
voltage across the load
is as shown in the right
hand diagram, during the
first half cycle.
During the second half
cycle, A and the anode
are negative, B and the
cathode are positive.
The diode is reverse
biased and no current
flows.
This is indicated by the
horizontal line in the
right hand diagram.
The diode only conducts
on every other half
cycle.
There is one pulse for
every cycle in. i.e 50
pulses per second (in
the UK)
The diode only conducts
during half the cycle.
Hence, HALF-WAVE
RECTIFICATION.
The rectified voltage is
DC (it is always
positive in value).
However, it is not a
steady DC but PULSATING
DC.
It needs to be smoothed
before it becomes
useful.
If the diode is reversed
then the output voltage
is negative.
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