Question

What is a logic gate? Draw the symbol and give the truth table for NOT gate. Why NOT the gate is called an inverter? 

Answer 1

Logic gate: A digital circuit with one or more input signals but only one output signal is called a logic gate. It is a switching circuit that follows a certain logical relationship between the input and output voltages.

Schematic symbol:  

NOT gate symbol

The truth table for NOT gate:

Input	Output
X	Y
0	1
1	0

Reason:

1. NOT gate has one input and one output.
2. It produces a ‘high’ output or output ‘1’ if the input is ‘0’. When the input is ‘high’ or ‘1’, its output is ‘low’ or ‘0’. 
3. That is, it produces a negated version of the input at its output.
   Hence, NOT gate is called an inverter.