Question

Light of different frequencies, whose photons have energies 3 eV and 18 eV respectively, successively illuminate a metal of work function 2 eV. The ratio of the maximum speeds of the emitted electrons will be ______.

Options

• 1 : 5

• 2 : 1

• 1 : 4

• 5 : 1

Answer 1

Light of different frequencies, whose photons have energies 3 eV and 18 eV respectively, successively illuminate a metal of work function 2 eV. The ratio of the maximum speeds of the emitted electrons will be 1 : 4.

Explanation:

E₁ = 3 eV, E₂ = 18 eV, Φ = 2 eV

`1/2 "m""V"_1^2 = "E"_1 - phi, 1/2 "mV"_2^2 = "E"_2 - phi`

`"V"_1^2/"V"_2^2 = 1/16 => "V"_1/"V"_2 = 1/4`