Question

The threshold wavelength of silver is 3800Å. Calculate the maximum kinetic energy in eV of photoelectrons emitted, when ultraviolet light of wavelength 2600Å falls on it.

(Planck’s constant, h =6.63 x 1O^-34J.s.,

Velocity of light in air, c = 3 x 10⁸ m / s)

Answer 1

Wavelength of silver, λ₁ = 3800 Aº

Wavelength of ultraviolet light, λ₂ = 2600 Aº

H = 6.63 × 10^-34 Js

Velocity of light in air, c = 3 × 10⁸ m/s

To calculate kinetic energy, K.E. = hv − hv_º

`"K.E."="hc"[1/lambda-1/lambda_o]`

`"K.E."=19.89xx10^-19[1/2.6-1/3.8]`

`"K.E."=(2.416xx10^-19)/(1.6xx10^-19)`

K.E. = 1.51 eV

Hence, the maximum kinetic energy emitted by the photoelectron is 1.51 eV.