Target Exam

CUET

Subject

Physics

Chapter

Dual Nature of Radiation and Matter

Question:

The surface of a metal is illuminated with the light of 400 nm. The kinetic energy of the ejected photoelectrons was found to be 1.68 eV. The work function of the metal is (hc = 1240 eV. nm)

Options:

3.09 eV

1.41 eV

1.51 eV

1.68 eV

Correct Answer:

1.41 eV

Explanation:

$∵\frac{hc}{λ}=\frac{1}{2}mv^2+\phi$

$⇒\phi=\frac{hc}{λ}-\frac{1}{2}mv^2=\frac{1240}{400}-1.68=1.41eV$