Question

The output of the circuit is low (zero) for:

(A) \( X = 0, Y = 0 \) 
(B) \( X = 0, Y = 1 \) 
(C) \( X = 1, Y = 0 \) 
(D) \( X = 1, Y = 1 \)
Choose the correct answer from the options given below:

• A. (A), (B) and (C) only
• B. (B), (C) and (D) only
• C. (A), (C) and (D) only
• D. (A), (B) and (D) only

Hint:

In an AND gate, the output is 1 only when both inputs are 1. In an OR gate, the output is 1 if at least one input is 1. Consider these truth tables when analyzing circuits.

Answer 1

The Correct Option is A

The circuit comprises two logic gates: an AND gate followed by an OR gate. The output is evaluated for each pair of \( X \) and \( Y \):
1. When \( X = 0 \) and \( Y = 0 \), the AND gate outputs \( 0 \). The OR gate also outputs \( 0 \), leading to a final output of \( 0 \). 
2. When \( X = 0 \) and \( Y = 1 \), the AND gate outputs \( 0 \). The OR gate outputs \( 1 \), but the AND gate's output of \( 0 \) dictates the final output remains \( 0 \). 
3. When \( X = 1 \) and \( Y = 0 \), the AND gate outputs \( 0 \). The OR gate outputs \( 1 \), yet the final output is still \( 0 \). 
4. When \( X = 1 \) and \( Y = 1 \), both the AND gate and the OR gate output \( 1 \), resulting in a final output of \( 1 \). 
Therefore, the output is low (\( 0 \)) for the following input combinations: - \( X = 0, Y = 0 \) - \( X = 0, Y = 1 \) - \( X = 1, Y = 0 \). 
Final Answer: (1) (A), (B) and (C) only.