1. The document is a physics investigatory project report by Khushal Mehta on building and testing a full wave rectifier circuit. 2. The circuit uses a transformer, four diodes arranged in a bridge configuration, capacitors, a resistor, and an LED to convert alternating current into direct current. 3. When tested, the circuit successfully rectified the alternating current into 12V of direct current, as measured by a voltmeter, and lit up the LED.

1. 2017 - 2018
PHYSICS INVESTIGATORY PROJECT

2. This is hereby to certify that ,the original and genuine
investigation work has been carried out to investigate
about the subject matter and the related data collection
and investigation has been completed solely, sincerely
and satisfactorily by KHUSHAL MEHTA of class XII ,
Kendriya Vidyalaya Banswara, regarding his project
titled “RECTIFIER”.
INTERNAL EX. EXTERNAL EX. PRINCIPAL
_______________ ________________ _________________

3. It would be my utmost pleasure to express my sincere
thanks to My Physics Teacher Mr. HARNISH NAGAR
in providing a helping hand in this project . Their
valuable guidance , support and supervision all through
this project titled “RECTIFIER” , are responsible for
attaining its present form.

4. To construct a Full Wave Bridge rectifier and show
that the (AC) alternating current is rectified into a
direct current (DC).
The aim is to -
1. Understand Rectification.
2. Explain center tapped full wave rectification.
3. Explain Bridge Full Wave Rectification.

5. I. Introduction
II. Theory
III. Materials required
IV. Circuit diagram
V. Procedure
VI. Working
VII. Observation And Result
VIII. Conclusion
IX. Bibliography

6. A rectifier is an electrical device that converts alternating
current (AC), which periodically reverses direction, to direct
current (DC), which flows in only one direction. The process is
known as rectification. Rectification produces a type of DC
that encompasses active voltages and currents, which are then
adjusted into a type of constant voltage DC, although this
varies depending on the current's end-use. The current is
allowed to flow uninterrupted in one direction, and no current
is allowed to flow in the opposite direction.
Physically, rectifiers take a number of forms, including
vacuum tube diodes, mercury-arc valves, copper and selenium
oxide rectifiers, semiconductor diodes, silicon-controlled
rectifiers and other silicon-based semiconductor switches.
Rectifier circuits may be single-phase or multi-phase. Most
low power rectifiers for domestic equipment are single-phase,
but three-phase rectification is very important for industrial
applications and for the transmission of energy as DC.

7. In half wave rectification, either the positive or negative half
of the AC wave is passed, while the other half is blocked.
Because only one half of the input waveform reaches the
output, it is very inefficient if used for power transfer.
A full-wave rectifier is exactly the same as the half-wave, but
allows unidirectional current through the load during the entire
sinusoidal cycle (as opposed to only half the cycle in the half-
wave). A full-wave rectifier converts the whole of the input
waveform to one of constant polarity (positive or negative) at
its output. Let us see our half wave rectifier example and
deduce the circuit. So, we have seen that this rectifier circuit
consists of two sources which have a phase difference along
with two diodes. When V1 is positive, V2 is negative. Hence
the top diode will be a short and the bottom diode will be an
open. On the other hand, when Vs1 is negative, Vs2 is positive.
Hence the bottom diode will be on and the top diode will be an
open circuit.
A full-wave rectifier can be constructed using Center-Tapped
transformer – which give us two shifted sinusoids so that
exactly one of the waveforms is positive at one time and two
diodes. As compared to the half wave rectifier we use two
diodes instead of one , one of the two diodes remains in
conduction in both of the half cycles. At any point in time,
only one of the diodes is forward biased. This allows for
continuous conduction through load.

8.  Connecting Wires
 A plug
 Single Lead Wire- 2m
 Three Nuts & Bolts 2-3cm length
 Circuit Board
 A Transformer (12V)
 A Resistor
 P-N Junction Diodes (4nos)
 A LED
 Insulation Tape, Blades, Soldering Wax, Soldering
Lead, Soldering Iron & Sand Paper.

9. Circuit diagram of a full wave rectifier :

10. Take the transformer and attach it to one end of the
circuit board. Attach the plug with the wire of
desired length and connect it to the transformer AC
In. now, take four diodes and connect the 4 diodes
into a loop. Connect the anode of diode D1 to the
anode of D2.
Connect the cathode of D2 to anode of D3.connect
the cathode of D3 to anode of D4 and connect the
anode of D4 to cathode of D1. The output of
transformers should be connected to A and C. Now,
take two capacitor and connect its –ve terminal to –
ve and +ve terminal to +ve. And connect both the
capacitors to B and D. Connect a resistor and a LED
to the capacitor. Attach wire from the capacitors and
connect it to the output device.

11. When the AC is supplied to the transformer, it step down
the 240V main supply to 12V. It has a capability of
delivering 700mA. The 12 volts AC appearing across the
secondary is the RMS value. The four diodes labelled D1
to D4 are arranged in “series pairs” with only two diodes
conducting current during each half cycle. The four
diodes labelled D1 to D4 are arranged in “series pairs”
with only two diodes conducting current during each half
cycle. During the positive half cycle of the supply, diodes
D1 and D2 conduct in series while diodes D3 and D4 are
reverse biased and the current flows through the load as
shown below.
The Positive Half-cycle

12. During the negative half cycle of the supply, diodes D3
and D4 conduct in series, but diodes D1 and D2 switch
“OFF” as they are now reverse biased. The current
flowing through the load is the same direction as before.
The Negative Half-cycle
In subsequent Half cycles of the AC Current the above
process are repeated. In both the half cycles it is clear that
current flows through the resistor in only one direction.
Even though the voltage across load is unidirectional it
will still contains a few AC components. This is filtered
and made smooth using a capacitor, which filters 99% of
the AC current. A resistor is then used to adjust the output
voltage. Capacitor also nearly filters all AC components
from supply and resistance is adjusted for the required
output. As this is a simple circuit, two capacitors and one
resistor are being used. The output Direct Current and
voltage light up the LED and other source connected with
it.

13. On connecting a voltmeter to the output of bridge
circuit 12V current is coming.

14. Rectifiers are found in all power supplies that
operate from an ac voltage source. Also the rectifier
is used as a power supply unit. The rectifier converts
the ac input voltage to a pulsating dc voltage. The
filter eliminates the fluctuations in the rectified
voltage and produces a relatively smooth dc voltage.
The regulator is a circuit that maintains a constant de
voltage for variations in the input line voltage or in
the load.
Working of A Rectifier :-

15.  Physics lab manual
 Wikipedia
 www.google.com
 www.olabs.edu.in