Question

In the following circuit what are $P$ and $Q$:

• A. P = 1, Q = 0
• B. P = 0, Q = 1
• C. P = 0, Q = 0
• D. P = 1, Q = 1

Answer 1

Answer: (B)

A $NAND$ gate gives an output $1$ if at least one of the inputs is zero.
Hence $Q$ is $1$ .
Therefore, the inputs for the upper $NAND$ gate are $1,1$.
Hence $P=0$.