Elementary Logic Gates (AND, OR, NOT Gate)

Elementary Logic Gates are the fundamental logic gates using which other logic gates are build.

There are three fundamental logic gates-

• AND Gate
• OR Gate
• NOT Gate 

1) AND Gate

 AND gate takes two or more inputs and results into one output. When all the inputs are high i.e. 1 then the output of AND Gate is high (1), and in rest all cases the output will be low i.e. 0 when any one of the inputs is low (0).

Logical Expression

F= A.B

Logic Symbol

The logic symbol for AND Gate is given below:

Truth Table

Here is the truth table of AND gate:

                                                                

2) OR Gate

OR gate also takes two or more inputs and results into one output. When any one of the inputs is high i.e. 1 then the output of OR Gate is high (1), and only in the case when all the inputs are low i.e. 0, the output will be low (0).

Logic Expression

F = A.B

 

Logic Symbol

 The logic symbol for OR Gate is given below:

Truth Table

3) NOT Gate

 NOT Gate is also known as Inverter Gate. In NOT Gate we have only one input and one output. It inverts the input and gives the output i.e. when input is high (1), the output is low (1) and when input is low (1), the output is high (1).  

Logical Expression

F = A’

Logic Symbol

 The logic symbol for NOT Gate is given below:

Truth Table