A UV lamp used for water purification operates at a power of 6.6 W and emits monochromatic light of wavelength 300 nm . How many photons are emitted by the lamp per second? (Take h = 6.6 10⁻³⁴ J s and c = 3 10^8 m/s )

Step-by-step solution

Energy of a single photon is given by E = hc Substituting the given values: E = 6.6 10⁻³⁴ 3 10^8 300 10⁻⁹ E = 19.8 10⁻²⁶ 3 10⁻⁷ = 6.6 10⁻¹⁹ J Let n be the number of photons emitted per second. The total power P is given by P = nE n = P E = 6.6 6.6 10⁻¹⁹ n = 10¹⁹ Answer: 10¹⁹