If a source of power 4 kW produces 10^20 photons/second

• Matter & Atoms
• EM Waves

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

1. microwaves
2. X rays
3. γ rays
4. ultraviolet rays

Answer

P = 4000 W

E = hc/λ 

λ = hc x 10²⁰ / 4000 = hc x 10¹⁷ / 4

λ = 3 x 10⁸ x 6.6 x 10-³⁴⁺¹⁷ / 4

= 19.8 x 10^-9 / 4

= 4.9 x 10^-9

λ = 49 X 10^-10

≈ 49 Å

Since 0.1 Å < λ < 100 Å, It is X-ray

The correct option is B.