Question

A metal has a work function \( \phi \). When light of wavelength \( \lambda \) is incident on it, the kinetic energy of the ejected electrons is 2 eV. Find the new kinetic energy of the ejected electrons when light of wavelength \( \lambda/2 \) is used.

• A. 3 eV
• B. 4 eV
• C. 6 eV
• D. 8 eV

Hint:

The kinetic energy of ejected electrons is the difference between the photon energy and the work function of the metal.

Answer 1

The Correct Option is C

The energy of a photon is inversely proportional to its wavelength. When the wavelength is halved, the energy of the photon doubles. 

Since the kinetic energy is the difference between the energy of the photon and the work function, doubling the energy of the photon increases the kinetic energy by 4 eV, making the new kinetic energy 6 eV.