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The output of an OR gate is connected to both the inputs of a NAND gate. The combination will serve as a

Asked in JEE Main 2011 · Gate combinations and truth tables

(1) NOT gate
(2) NOR gate
(3) AND gate
(4) OR gate

Answer: (2) NOR gate

Step-by-step solution

A NAND with its inputs tied acts as NOT.

Output =A+B: NOR.

Why the other options are wrong

(1) The combination has two inputs, not one.
(3) Not obtainable; there is no AND of the inputs.
(4) Forgets that the tied NAND inverts.

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