Question

The truth tables of logic gates A, B, C, D are given here. Identify them correctly.

• A. A: AND, B: OR, C: NAND, D: NOR
• B. A: OR, B: AND, C: NOR, D: NAND
• C. A: OR, B: NOR, C: NAND, D: AND
• D. A: OR, B: NOR, C: AND, D: NAND

Answer 1

Answer: (B)

(A) : Truth table shows that the output is low when both the inputs are low and the output is high when either of the input is high. Thus this truth table represents the $OR$ gate.

(B) : Truth table shows that the output is high when both the inputs are high and the output is low when either of the input is low. Thus this truth table represents the $AND$ gate.

(C) : Truth table shows that the output is high when both the inputs are low and the output is low when either of the input is high. Thus this truth table represents the $NOR$ gate. Also this truth table is the inverse to that of (A).

(D) : Truth table shows that the output is low when both the inputs are high and the output is high when either of the input is low. Thus this truth table represents the $NAND$ gate. Also this truth table is the inverse to that of (B).