The power obtained in a reactor using U²³⁵ disintegration is 1000 kW. The mass decay of U²³⁵ per hour is

Options

(a) 10 microgram
(b) 20 microgram
(c) 40 microgram
(d) 1 microgram

Correct Answer:

40 microgram

Explanation:

E = mc² m = E / c² so, mass decay per second.
dm/ dt = 1/c² . dE/ dt = 1/c² (Power in watt)
= 1 / (3 x 10⁸)² x 1000 x 10³
and mass decay per hour = dm/ dt x 60 x 60
= 1 / (3 x 10⁸)² x 10⁶ x 3600 = 4 x 10⁻⁸ kg = 40 microgram