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In a digital circuit, logical value A = 1 or B = 1 corresponds to a voltage of 3 V at the input, and A = 0 or B = 0 corresponds to 0 V. Y is the voltage at the output point. The truth table of this circuit is:

1. A B Y 0 0 0 1 0 0 0 1 0 1 1 1
2. A B Y 0 0 0 1 0 1 0 1 1 1 1 1
3. A B Y 0 0 0 1 0 0 0 1 0 1 1 0
4. A B Y 0 0 1 1 0 1 0 1 1 1 1 0

Correct answer: A B Y 0 0 0 1 0 1 0 1 1 1 1 1

Solution

The truth table in option B (Y=0 only when both A=B=0, else Y=1) corresponds to an OR gate. This is the most common circuit described in JEE problems with two inputs and diode/transistor networks where output is high if either input is high.

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