Monochromatic radiation emitted when electron on hydrogen atom jumps from first excited to the ground state irradiates a photosensitive material. The stopping potential is measured to be `3.57V`. The threshold frequency of the material is

Options

A. `1.6 xx 10^(15)Hz`
B. `2.5 xx 10^(15) Hz`
C. `4 xx 10^(15) Hz`
D. `5 xx 10^(15) Hz`

Answer

1

Explanation

Energy of photon `= E_(2) - E_(1)`
`=(-(13.6)/(4))-(-13.6)=1.2 eV.`
`KE = eVd_(0) = 3.57 eV`
`w_(0) = 10.2 - 3.57 = 6.63 eV`
`f_(0) = (6.63 eV)/(h) = 1.6 xx 10^(15)` Hz.