Q. An electric bulb is marked 100 W, 230 V. If the supply voltage drops to 115 V, what is the total energy produced by the bulb in 10 min?
A) 30 kJ
B) 20 kJ
C) 15 kJ
D) 10 kJ
Explanation
(c) $R = \frac{230 \times 230}{100} = 529\ \Omega$
$\therefore H = \frac{V^{2}}{R} \times t = \frac{115 \times 115}{529} \times 10 \times 60 = 15\ kJ\ $
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.