JEE Main 2021 · 17 March · evening · Single correct · +4 / −1
Which one of the following will be the output of the given circuit?
- (a) XOR Gate
- (b) NOR Gate
- (c) NAND Gate
- (d) AND Gate
Answer and solution
Answer (a) XOR Gate
Solution
Physics sir · 3 steps
Follow each branch separately: the top one gives NAND, the bottom one gives OR, and the last AND joins them.
- Top branch. A and B go into an AND gate, and its output passes through a NOT gate. That makes the top line A · B̅, which is NAND.
- Bottom branch. A and B also go into an OR gate, giving A + B. The final AND gate multiplies the two branches.
Y = (A · B̅)·(A + B)
A, B A · B̅ A + B Y 0, 0 1 0 0 0, 1 1 1 1 1, 0 1 1 1 1, 1 0 1 0 - So. Y is 1 only when exactly one input is 1. That is the XOR gate, option (a).
The idea to keep. For any gate combination, write the Boolean expression branch by branch, then check all four input pairs in a truth table. Output 1 only for unequal inputs means XOR.
Answer from the NTA final answer key. Solution by PrepWiser.