question_answer

Which one of the following gates will have an output of 1?                                                    [AIPMT 1998]

A)        A                    

B)       B

C)  C        

D)                   D

Correct Answer: C

Solution :

[a] Gate A is NAND gate, is output will be

\[{{Y}_{A}}=\overline{1.1}=\bar{1}=0\]

[b] Gate B is NOR gate, is output will be

\[{{Y}_{B}}=\overline{1+1}=\bar{1}=0\]

[c] Gate C is NAND gate, its output will be

\[{{Y}_{C}}=\overline{0.1}=\overline{0}=1\]

[d] Gate D is XOR gate, its output will be

\[{{Y}_{D}}=0\oplus 0=0\cdot \overline{0}+\overline{0}\cdot 0=0\]

Thus, gate [c] will give an output of 1.

Note:    Option [d] represents a logic symbol of exclusive OR gate or XOR gate. Its descriptive form showing is Boolean expression may be represented as: