Given below are two statements: Statement I: Among microwaves, infrared rays and ultraviolet rays, ultraviolet rays are most effective for emission of electrons from a metallic surface.
Statement II: Above threshold frequency, the maximum kinetic energy of photoelectrons is inversely proportional to incident frequency. Choose the correct answer.

Question

Given below are two statements: Statement I: Among microwaves, infrared rays and ultraviolet rays, ultraviolet rays are most effective for emission of electrons from a metallic surface.

Statement II: Above threshold frequency, the maximum kinetic energy of photoelectrons is inversely proportional to incident frequency. Choose the correct answer.

G1 Physics · Accepted Answer

Ultraviolet radiation has the highest frequency among the three listed regions, so it has the highest photon energy and is the most effective for photoelectric emission. Einstein's photoelectric equation is Kₘₐₓ = hf - hf₀ Thus Kₘₐₓ increases linearly with frequency above threshold; it is not inversely proportional to frequency. Therefore Statement I is true and Statement II is false. Hence option C follows.