Name the logic gate equivalent to the diagram attached

Solution

Physics sir · 3 steps

Each closed switch shorts the LED, so it glows only when both switches stay open: that is NOR.

1. Read the circuit. Switch A, switch B and the LED are all connected between the same top rail (at +5 V) and the same bottom rail. So the three are in parallel, and this whole group is in series with R to ground. A closed switch counts as input 1, and a glowing LED counts as Y = 1.
2. Closed switch shorts LED. A closed switch is a zero-resistance path in parallel with the LED. Current takes that path, the voltage across the LED drops to zero, and the LED stays dark. This happens if either switch is closed.

   A	B	What happens	Y
   0	0	No short, current flows through LED and R	1
   0	1	B shorts the LED	0
   1	0	A shorts the LED	0
   1	1	Both short the LED	0

3. So. The output is high only when both inputs are 0, so Y = A + B̅. This is the NOR gate, option (a).

The idea to keep. If switches sit in parallel with the bulb, they kill it when closed, so the output is inverted. Parallel switches across the bulb give NOR, and series switches across it give NAND.

Answer from the NTA final answer key. Solution by PrepWiser.