Which gate is the opposite of OR?

Which gate is the opposite of OR?

• A. XOR gate
• B. NOR gate
• C. NAND gate
• D. AND gate

Answer: (B)

Opposite here means the negation of the OR operation. An OR gate outputs 1 if any input is 1. If you invert that result, you get a gate that outputs 1 only when all inputs are 0. That gate is the NOR gate. For two inputs, OR yields 0,0 -> 0 and 0,1 -> 1, 1,0 -> 1, 1,1 -> 1; NOR inverts these to 0,0 -> 1 and 0,1 -> 0, 1,0 -> 0, 1,1 -> 0. So the opposite of OR is NOR. The other gates don’t perform this complement: XOR is true when inputs differ, AND is true only if both are true, and NAND is the negation of AND, not the negation of OR.

Opposite here means the negation of the OR operation. An OR gate outputs 1 if any input is 1. If you invert that result, you get a gate that outputs 1 only when all inputs are 0. That gate is the NOR gate. For two inputs, OR yields 0,0 -> 0 and 0,1 -> 1, 1,0 -> 1, 1,1 -> 1; NOR inverts these to 0,0 -> 1 and 0,1 -> 0, 1,0 -> 0, 1,1 -> 0. So the opposite of OR is NOR. The other gates don’t perform this complement: XOR is true when inputs differ, AND is true only if both are true, and NAND is the negation of AND, not the negation of OR.