Physics · Electrical energy and power, electrical resistivity and conductivity
Assertion When current through a bulb decreases by the glow of bulb decreases by
Assertion When current through a bulb decreases by \( 0.5 \%, \) the glow of bulb decreases by \( 1 \% \) Reason Glow (Power) which is directly proportional to square of current.
- A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
- B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
- C. Assertion is correct but Reason is incorrect
- D. Both Assertion and Reason are incorrect
Step-by-step solution
Power dissipated in a bulb (resistive) is P = I^2 R, so proportional to square of current. A 0.5% decrease in current leads to approximately 1% decrease in power (since (0.995)^2 ≈ 0.990), so the glow decreases by 1%. Hence both statements are correct, and the reason correctly explains the assertion.