Question

Some satellites use nuclear power. (a) If such a satellite emits a 1.00-W flux of γ rays having an average energy of 0.500 MeV, how many are emitted per second?

a) (1.25 × 10¹⁶) γ rays/s
b) (1.91 × 10¹⁶) γ rays/s
c) (1.45 × 10¹⁶) γ rays/s
d) (1.35 × 10¹⁶) γ rays/s

Answer 1

To find the number of γ rays emitted per second by the satellite, convert the average energy to joules and then divide the power output of the satellite by the energy per γ ray.

Step-by-step explanation:

To calculate the number of γ rays emitted per second by a satellite using nuclear power, we must first convert the average energy of the rays from MeV to joules. The energy E of a single γ ray (photon) is given by E = (0.500 MeV) (1.602 × 10−12 J/MeV) = 8.01 × 10−13 J. If the satellite emits a 1.00-W flux of γ rays, this means it is emitting 1.00 joule of energy per second. The number of γ rays emitted per second (n) can be found using the formula n = Power/Energy per γ ray, thus n = (1.00 J/s) / (8.01 × 10−13 J) = 1.25 × 1016 γ rays/s.