question_answer

                The truth table given below is for which gate?                                                                                   

Input		Output
A	B	C
0	0	1
0	1	1
1	0	1
1	1	0

A)                 XOR

B)                 OR

C)                 AND                      

D)                 NAND

Correct Answer: D

Solution :

                The given truth table gives                 0 * 0 = 1                 0 * 1 = 1                 1 * 0 = 1                 1 * 1 = 0                 The above data represents the expression                 \[Y=\overline{A\,\,.\,\,B}\]                 This expression is the Boolean expression of NAND gate.                 Note:    NAND gate used as OR function                                   Thus \[\overline{A\cdot B}=\overline{A}+\overline{B}\]                 This is according to De Morgan?s theorem which states that complements of produces equals the sum or vice-versa.