Question

Identify the gate in the figures_________

(A)AND
(B)XOR
(C)NOR
(D)NAND

Answer 1

Hint: We need to identify the output of each of these gates to inspect the final output through various combinations of input. The final output that we get will be the output of the entire system of gates and we can identify the gate with the input of the first gate and the output of the last gate.

Complete step by step answer:
The gate that is used repeatedly in the given question is a NOR gate. The NOR gate is a combination of OR gate and NOT gate. Thus the output is the inverted output of the OR gate.
The logic table for a NOR gate is given as follows:

A	B	A+B	Output
0	0	0	1
0	1	1	0
1	0	1	0
1	1	1	0

So here we take the gates A and B as input gates and the gate 4 as the output gate,

A NOR gate is basically a NOT gate when it has got one terminal. Following this rule and the logic table for NOR gate with 2 terminals, wechat out the table for the gate given in the question above as follows:

A	B	Output of A and B	C	D
0	0	1, 1	0	1
0	1	1,0	0	1
1	0	0,1	0	1
1	1	0,0	1	0

The output that we have got in the form of the logic table as charted above is the same as the output for a NAND gate.

So the correct identification for the type of gate for the gate given in question is (D) NAND gate.

Additional Information:
The NAND gate and the NOR gates are known as universal gates as they can be used as fundamental gates to build up any other gate like AND, OR or NOT gate. In this question, 4 NOR gates are used and a NAND gate is generated.

Note:
The function and significance of the basic logic gates must be known to solve such kinds of problems. With the help of the logic tables, the answers to such problems can quickly be deduced by checking for the 4 sets of binary inputs for logic gates with 2 terminals.