question_answer

Sodium and copper have work functions \[2.3\] eV and \[4.5\] eV respectively. Then, the ratio of the wavelengths is nearest to     [AIEEE 2002]

A) \[1:2\]

B) \[4:1\]

C) \[2:1\]

D) \[1:4\]

Correct Answer: C

Solution :

[c] Work function

(here, they are interested in asking threshold wavelength)

where,  Planck's constant,  velocity of light.

Therefore,

(nearly)