JEE Main 2026 Jan 21 Shift 1, Physics Q17: Logic Gates

Trace through the circuit. The first two NOR gates have their inputs tied, so they act as inverters: $P=\bar{A}$, $Q=\bar{B}$.

The third NOR gate: $R=\overline{P+Q}=\overline{\bar{A}+\bar{B}}$. By De Morgan's law this equals $A\cdot B$.

The final inverter gives $\overline{A\cdot B}$, which is the NAND function.