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The correct Boolean operation represented by the circuit diagram drawn is

Asked in NEET 2019 · Waveforms, switches and diode gates

Figure: Waveforms, switches and diode gates
Answer: (4) NAND

Step-by-step solution

Idea: the two switches are in series with each other and together they bridge the LED, so closing both provides a path around it.

With both open the bypass is broken, so the current has to pass through the LED and it glows: output 1.

With only one closed the bypass is still broken at the other switch, so the LED still glows: output 1.

With both closed the bypass is complete and shorts the LED out, so it goes dark: output 0.

The pattern 1,1,1,0 is the NAND gate.

Why the other options are wrong

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