This document is a physics project submitted by Ashish Kumar to his teacher, Mr. C.S. Jha, on the topic of rectifiers. It describes constructing a full wave bridge rectifier to convert alternating current (AC) to direct current (DC). The project aims to understand rectification and explain center tapped and bridge full wave rectification. It details the circuit components used, including a transformer, diodes, capacitors and resistor. The document explains how the full wave bridge rectifier works during each half cycle to allow current flow in one direction only, producing a pulsating DC output that is filtered by the capacitors. Testing showed the rectifier produced a 12V DC current.

1. KENDRIYA VIDYLAYA NO.2
DELHI CANTT
2019 - 2020
PHYSICS INVESTIGATORY PROJECT
SUBMITTED BY :- ASHISH KUMAR
CLASS :- XII “A”
SUBMITTED TO :- MR. C.S. JHA

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 ASHISH KUMAR of class XII-A ,
Kendriya Vidyalaya No.2 Delhi Cantt, regarding his
project titled “RECTIFIER”, under the guidance of
Mr. C.S. JHA, PGT(Physics) during the academic year
2019-2020
Mr. C.S. JHA EXTERNAL EXAMINER
PGT (Physics)

3. It would be my utmost pleasure to express my sincere
thanks to My Physics Teacher Mr. C.S. JHA 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. This project also bears an imprint of many other
people. I sincerely thank to my project guide and
Mr. Prem Pal (Lab Attendant) for guidance and
encouragement in carrying out this project work.
ASHISH KUMAR
Kendriya Vidyalaya No. 2
Delhi Cantt

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.

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
vaccum 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 2-3 cm length
❖ Circuit board
❖ A Transformer (12 V)
❖ A Resistor
❖ p-n junction diode (4 nos)
❖ A LED
❖ Insulation Tape, Blades, Soldering Wax,
Soldering Iron, Soldering Lead & 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.
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
negative 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
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