Question

In a photoelectric experiment, with light of wavelength λ, the fastest electron has speed v. If the exciting wavelength is changed to 3λ/4, the speed of the fastest emitted electron will become

• A. √((3)/(4))v
• B. √((4)/(3))v
• C. less than √((4)/(3))v
• D. greater than √((4)/(3))v

Hint:

Photoelectric speed depends on excess photon energy.

Answer 1

The Correct Option is C

Kinetic energy depends on frequency minus threshold frequency. Increase in frequency does not scale linearly, hence speed is less than √((4)/(3))v.