Logic Gates

Correct Answer: B (NOR)

Explanation: The circuit represents a NOR gate because:

• Structure: A NOR gate is equivalent to an OR gate followed by a NOT gate (inverter).
• Behavior: The output is HIGH (1) only when both inputs are LOW (0), matching the NOR truth table.

Why other options are incorrect:

• A (OR): OR gates lack the final inversion step.
• B (AND): AND gates require both inputs to be HIGH for a HIGH output.
• C (NOT): NOT gates have only one input, not two.

Key Insight: The inversion (bubble) at the output signifies the NOT operation combined with OR, defining NOR logic.

This is a case of an AND gate. The input and output relationships are shown below:

Therefore, the output is:

Since , the output can be written as:

Thus, the output of the AND gate is .

Correct Answer: B

Explanation:

The given truth table represents the output behavior of a logic gate based on the inputs A and B. We need to identify the type of gate based on the given outputs.

The first table shows the following output for inputs A and B:

Upon analyzing the truth table, we can observe that the output is 1 when either A is 1 and B is 0, or when A is 0 and B is 1, which matches the behavior of an Exclusive OR (XOR) gate.

The second table represents the truth table for an OR gate, the third table represents the truth table for an AND gate, and the fourth table represents the truth table for a NAND gate. Therefore, the correct answer is B, which corresponds to the XOR gate.