ARMY PUBLIC SCHOOL

PUNE

SESSION: 2023 - 2024

PHYSICS INVESTIGATORY PROJECT
“LOGIC GATES”

NAME: SHELAKE PRACHI PRAVIN

CLASS: XII ‘B’
ROLL NO.:
 CERTIFICATE

This is to certify that Shelake Prachi Pravin, a student of

Class XII-B. Roll no.___________ of Army Public School,
Pune has satisfactorily completed the Physics
Investigatory Project on the topic “Logic gates" for the
Academic Session 2023-2024.

I certify that this project is up to my expectations and as

per the guidelines of CBSE.

__________________ _________________
Mrs. Seema Kumari Mrs. Anita Sharma
(Physics Teacher) (Principal)

External Examiner's Signature

 ACKNOWLEDGEMENT

In this endeavour, I was constantly guided and helped

by the following people, without whom, this project
would not have been possible.

Firstly, I would like to thank the principal Mrs. Anita

Sharma for giving me a chance to work on this project.

I would also like to thank subject teacher Mrs. Seema

Kumari for her constant and appreciable support
throughout the project.

Lastly, I express my thanks to my family for extending

their support throughout.
 CONTENT

 Introduction

 Principle

 Basic Gates

 The OR Gate
 The AND Gate
 The NOT Gate
 The NOR Gate
 The NAND Gate
 The EX-OR Gate
 The EX-NOR Gate

 Experiments
 To design and stimulate the OR gate circuit
 To design and stimulate the AND gate circuit
 To design and stimulate the NOT gate circuit

 Conclusion
 INTRODUCTION

GATE-A gate is defined as a digital circuit which follows

some logical relationship between the input and output
voltages. It is a digital circuit which either allows a signal
to pass through or stop it. The logic gates are building
blocks at digital electronics. They are used in digital
electronics to change one voltage level into another
according to some logic statement relating to them.

Truth Table: A logic gate may have one or more than one
inputs, but it has only one output. The relationship
between the possible values of input and output voltages
are expressed in the form of a table called truth table.
Truth table of a logic gate is a table that shows all the
inputs and outputs that are possible for the logic gates.

Boolean algebra - The algebra which is based on binary

nature of the logic gates.

Boolean Expressions: They are the logical statement

which are followed by logical gates.
 PRINCIPLE

Any Boolean algebra operation can be associated with

inputs and outputs represent the statements of Boolean
algebra. Although these circuits may be complex, they
may all be Constructed from three basic devices. We
have three different types of logic gates. These are the
AND gate, the OR gate and the NOT gate.

LOGICAL STATEMENTS

1 0
High Low
Positive Negative
On Off
Close Open
Conducting Non-Conducting
Right Wrong
True False
Yes No
 BASIC GATES

1.OR Gate: The OR gate is a digital logic gate with ‘n’

inputs and one output, that performs logical conjunction
based on the combinations of its inputs. The output of the
OR gate is true only when one or more inputs are true. If
all the Input of the gate are false, then only the output of
the OR gate is false. The symbol and truth table of an OR
gate with two inputs is shown below.

2.AND Gate: The AND gate is a digital logic gate with ‘n’
inputs one output, which performs logical conjunction
based on the combinations of its inputs. The output of this
gate is true only when all the inputs are true. When one
or more inputs of the AND gate’s input are false, then only
the output of the AND gate is false. The symbol and truth
table of an AND gate with two inputs is shown below.
3.NOT Gate: The NOT Gate is a digital logic gate with
one input and one output that operates an inverter
operation of the input. The output of the NOT gate is the
reverse of the input. When the input of the NOT gate is
true then the output will be false and vice versa. The
symbol and truth table of a NOT gate with one input is
shown below.

4.NAND Gate: The NAND gate is a digital logic gate

with ‘n’ inputs and one output, that performs the operation
of the AND gate followed by the operation of the NOT
gate. NAND gate is designed by combining the AND and
NOT gates. If the input of the NAND gate high, then the
output of the gate will be low. The symbol and truth table
of the NAND gate with two inputs is shown below.
5.NOR Gate: The NOR gate is a digital logic gate with
n inputs and one output, that performs the operation of
the OR gate followed by the NOT gate. NOR gate is
designed by combining the OR and NOT gate. When any
one of the inputs of the NOR gate is true, then the output
of the NOR gate will be false. The symbol and truth table
of the NOR gate with the truth table is shown below.

6.Exclusive-OR Gate: The Exclusive-OR gate is a

digital logic gate with two inputs and one output. The short
form of this gate is Ex-OR. It performs based on the
operation of the OR gate. If any one of the inputs of this
gate is high, then the output of the EX-OR gate will be
high. The symbol and truth table of the EX-OR are shown
below:
7.Exclusive-NOR Gate: The Exclusive-NOR gate is
a digital logic gate with two inputs and one output. The
short form of this gate is Ex-NOR. It performs based on
the operation of the NOR gate. When both the inputs of
this gate are high, then the output of the EX-NOR gate
will be high. But, if any one of the inputs is high (but not
both), then the output will be low. The symbol and truth
table of the EX-NOR are shown below.

APPLICATIONS:
The applications of logic gates are mainly determined
based upon their truth table, i.e., their mode of operations.
The basic logic gates are used in many circuits like a
push-button lock, light-activated burglar alarm, safety
thermostat, an automatic watering system, etc.
 EXPERIMENTS

1] OR Gate
Aim: To design and stimulate the OR gate circuit.
.
Components: Two ideal p-n junction diode (D1 and D2).

Theory and Construction: An OR gate can be realized by

the electronic circuit. making use of two diodes D1 and
D2. A

B Y

Hear the negative terminal of the battery is grounded and

corresponds to the 0 level, and the positive terminal of the
battery corresponds to level 1.
Observation:
Truth table
INPUT INPUT OUTPUT
A B Y=(A+B)
0 0 0
0 1 1
1 0 1
1 1 1

Conclusion:
 If the switch A and B are kept open (A=0, B=0), then
bulb does not glow, hence y=0.
 If switch A is kept closed and B is kept open (A=1,
B=0) then bulb does not glow. hence Y=1.
 If switch A is kept open and B is kept closed (A=0,
B=1), then bulb does not glow hence Y=1.
 If switch A and B both are kept closed (A=1, B=1)
then bulb glows hence Y=1.

.
2] AND Gate
Aim: To design and stimulate the AND Gate circuit.

Components:
 Two ideal p-n junction diode (D1 and D2)
 A resistance R.

Theory and Construction: An AND gate can be realized

by the electronic circuit, making use of two diodes D1 and
D2. The resistance R is connected to the positive terminal
of a 5V battery permanently.
A B

Here the negative terminal of the battery is grounded and

corresponds to the 0 level, and the positive terminal of the
battery corresponds to the level 1. The output Y is the
voltage at C with respect to earth.
Observation:
Truth table
INPUT INPUT OUTPUT
A B Y= (A.B)
0 0 0
0 1 0
1 0 0
1 1 1

Conclusion:
 If the switch A and B are kept open (A=0, B=0), then
bulb does not glow., hence Y=0.
 If switch A is kept closed and B is kept open (A=1,
B=0), then bulb does not glow, hence Y=0.
 If switch A is kept open and B is kept closed (A=0,
B=1), then bulb does not glow, hence Y=0.
 If both switch A and B are kept closed (A=1, B=1),
then bulb glows, hence Y=1.
3] NOT Gate
Aim: To design and stimulate the NOT Gate circuit.

Components: An ideal n-p-n transistor.

Theory and Construction: A NOT gate cannot be realized

by using diodes. However, an electronic circuit of NOT
gate can be realized by making use a n-p-n transistor.

The base of the transistor is connected to the Input A

through a resistance Rb and the emitter is earthed. The
collector is connected to 5V battery. The output Y is
voltage at C with respect to earth.
Observation:
Truth table
INPUT OUTPUT
A Y
0 1
1 0

Conclusion:
 If the switch A is kept open(A=0) then bulb glows,
hence Y=1
 If the switch A is kept closed(A=1) then bulb does
not glow, hence Y=0.
 CONCLUSION

Logic gates are used for a variety of gadgets that we use

on a daily basis. Depending on the application and truth
table, various sorts of gates are utilized. Flip flops, which
are certainly built using gates, are used to store memory
in mobile phones, laptops, and other electronic devices.
They’re also found in microprocessors’ Arithmetic Logic
Units (ALUs), which include adders, multipliers, and other
functions. Logic gates are used to create these circuits.
logic gates are utilized in a variety of technologies. These
are components of chips (ICs), which are components of
computers, phones, laptops, and other electronic
devices.
Logic gates may be combined in a variety of ways, and
a million of these combinations are necessary to make
the newest gadgets, satellites, and even robots.
Simple logic gate combinations can also be found in
burglar alarms, buzzers, switches, and street lights.
Because these gates can make a choice to start or stop
based on logic, they are often used in a variety of
sectors.
Logic gates are also important in data transport,
calculation, and data processing. Even transistor-
transistor logic and CMOS circuitry make extensive use
of logic gates.
 BIBLIOGRAPHY

 Physics NCERT Textbook

 www.studocu.com

 www.geeksforgeeks.org

 www.wikipedia.com