Question

Following gates section is connected in a complete suitable circuit.

For which of the following combination, bulb will glow (ON):

• A. A = 0, B = 1, C = 1, D = 1
• B. A = 1, B = 0, C = 0, D = 0
• C. A = 0, B = 0, C = 0, D = 1
• D. A = 1, B = 1, C = 1, D = 0

Answer 1

Answer: (B)

A = 1, B = 0, C = 0, D = 0

Answer 2

The bulb will glow if it experiences a potential drop across it. This requires one end of the bulb to be at a high state (1) and the other end to be at a low state (0).

In Option (2) , setting $A = 1, B = 0, C = 0, D = 0$ satisfies this condition, as it results in the output of the OR gate being high, creating the required potential drop across the bulb.