Light of wavelength λ strikes a photo-sensitive surface and electrons are ejected with kinetic energy E. If the kinetic energy is to be increased to 2E, the wavelength must be changed to λ' where -
Answer & explanation
Correct answer: option 3
If $λ'=λ/2 ⇒E_2>2E_1$
But here $E_2>2E_1$ So $λ'=λ/2$
So answer is $λ>λ'>λ/2$