Question

If a source of power 4kW produces 10²⁰photons/second, the radiation belongs to a part of the spectrum called
(a) γ-rays 

(b) X-rays

(c) ultraviolet rays 

(d) microwaves

Answer 1

(b) : Here,
Power of a source, P = 4kW = 4 × 10³ W
Number of photons emitted per second, N = 10²⁰