investigatory projects class 12

1. Aim
To understand the working of half wave rectifier using p-n junction
diodes and to design a circuit diagram of half wave rectifier using step
down transformer (220V AC – 12V AC), diodes, LED and suitable
resistances.

2. Introduction and principle of a rectifier

3. Apparatus used
Step-down transformer (220V AC – 12V AC)
p-n junction diode (IN 4007)
Circuit board
Wires
9V battery and battery connector
LED (5mm, 1.5V)
Resistors
Push button type toggle switch

4. Theory and working
1.)Working of p-n junction diode in forward and reverse biasing

5. 2.)Half wave rectifier

6. 3.)Circuit diagram used in making of half wave rectifier and its working

7. When the push button is in ‘released state’ then terminal ‘2’ is
connected to terminal ‘3’, when push button is in ‘active or pressed’
then terminal ‘2’ is connected to terminal ‘1’.
The push button connected to diode is ‘button 1’ and the other one is
‘button 2’.
When ‘button 1’ is pressed and ‘button 2’ is released then it is
equivalent to first half wave of AC. In this state, diode is forward biased
and current flows through LED.
When ‘button 2’ is pressed and ‘button 1’ is released then it is
equivalent to second half wave of AC. In this state, diode is reverse
biased and current does not flow through LED.

8. Uses of rectifiers
Write yourself
Conclusion
The output of half wave rectifier clearly shows that potential difference
is not stable but it is fluctuating, which shows that current is flowing
only during positive half cycle of AC and negative half cycle of AC is
rectified.
Sources of errors
Write yourself
Precautions
Keep away from high voltage current.

9. Bibliography
NCERT textbook of class 12
Physics by S.L.Arora
Circuits available on internet