When the wavelength of radiation falling on a metal is changed from 500 nm   to   200 nm , the…

When the wavelength of radiation falling on a metal is changed from 500nm to 200nm, the maximum kinetic energy of the photoelectrons becomes three times larger. The work function of the metal is close to:
  1. 0.81eV
  2. 1.02eV
  3. 0.52eV
  4. 0.61eV

Solution

KEmax=hcλ-ϕ=hc500-ϕ   .....(i)

Now,

3KEmax=hc200-ϕ

   .....(ii)

From equation (i) and (ii)

iii=31=hc200-ϕhc500-ϕ

Put the value of hc=1237.5 and solving ϕ=0.61eV

Asked in: JEE Main 2020 (03 Sep Shift 1)

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