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 given circuit consists of two logic gates: 
1. The first gate is an AND gate. 
2. The second gate is an OR gate. Let's evaluate the output for each pair of \( X \) and \( Y \): 
- When \( X = 0 \) and \( Y = 0 \), the output of the AND gate is \( 0 \) because both inputs are zero. The output of the OR gate is also \( 0 \), since the OR gate only outputs 1 when at least one input is 1. Thus, the final output is low (zero). - When \( X = 0 \) and \( Y = 1 \), the output of the AND gate is \( 0 \). The OR gate outputs \( 1 \), but since the AND gate's output is zero, the final output is still low. 
- When \( X = 1 \) and \( Y = 0 \), the output of the AND gate is \( 0 \) because the second input is zero. The OR gate outputs \( 1 \), but the final output will still be low. 
- When \( X = 1 \) and \( Y = 1 \), the AND gate outputs \( 1 \), and the OR gate also outputs \( 1 \), resulting in a high output. 
Thus, the output is low for the following combinations: - (A) \( X = 0, Y = 0 \) - (B) \( X = 0, Y = 1 \) - (C) \( X = 1, Y = 0 \) 
Final Answer: (1) (A), (B) and (C) only.