Q. The power obtained in a reactor using U-235 disintegration is 1000 kW. The mass decay of U-235 per hour is
A) 1 microgram
B) 10 microgram
C) 20 microgram
D) 40 microgram
Explanation
[Solution from source] Energy produced in one hour = 10⁶ W × 3600 s = 3.6 × 10⁹ J. Mass converted = E/c² = 3.6 × 10⁹/(9 × 10¹⁶) = 4 × 10⁻⁸ kg = 40 μg. Forgetting the factor 3600 or using kW as W gives the smaller options. Answer (4).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.