Question

In a half adder circuit, what happens if both inputs are 1?

• A. The sum is 1 and the carry is 0
• B. The sum is 0 and the carry is 1
• C. Both sum and carry are 1
• D. Both sum and carry are 0

Hint:

In a half adder, when both inputs are 1, the sum wraps to 0 and the carry becomes 1 — just like in binary addition!

Answer 1

The Correct Option is B

A half adder is a basic combinational logic circuit used to add two binary digits. It provides two outputs:

• Sum — computed using an XOR gate: \( \text{Sum} = A \oplus B \)
• Carry — computed using an AND gate: \( \text{Carry} = A \cdot B \)

When both inputs \( A = 1 \) and \( B = 1 \), we have: \[ \text{Sum} = 1 \oplus 1 = 0 \] \[ \text{Carry} = 1 \cdot 1 = 1 \] So, the result of this addition is:

• Sum = 0
• Carry = 1