NEET | 2016Wave motionHard

Question

When a metallic surface is illuminated with radiation of wavelength λ, the stopping potential is V. If the samesurface is illuminated with radiation of wavelength 2λ, the stopping potential is V/4. The threshold wavelengthfor the metallic surface is:

Options

A.

4λ

B.

5λ

C.

52λ

D.

3/2

Solution

In photo electric effects
eV0 = 48 - W
eV0 = hcλ-w
eV = hcλ-w  .... (i)
ev4=hc2λ-w    ....….(ii)
From (i) and (ii)
hcλ-w=4hc2λ-w
hcλ-w=2hcλ-4w
3W =hcλ⇒W=hc3λ
hcλmax=hc3λ⇒λmax= threshold wavelength 3λ

Create a free account to view solution

View Solution Free
Topic: Wave motion·Practice all Wave motion questions

More Wave motion Questions

The period of SHM of a particle is 12 s. The phase difference between the position at t = 3s and t = 4s will be :...The path difference between two interference waves at a point on a screen is 11.5 times the wavelength. The point is :-...The prong of a electrically operated tuning fork is connected to a long string of μ = 1 kg/m and tension 25 N. The maxim...The diagram below shows two pulses traveling towards each other in a uniform medium with same speed. Pulses in the figur...If the air column in a pipe which is closed at one end, is in resonance with a vibrating tuning fork at a frequency 260 ...