Two radiations of photons energies 1 eV and 2.5 eV, successively illuminate a photosensitive metallic surface of work function 0.5 eV. The ratio of the maximum speeds of the emitted electrons is -

Options

A. `1:5`
B. `1:4`
C. `1:2`
D. `1:1`

Answer

C

Explanation

If E is the energy of incident photon and W the work function, then `E_W_0="available energy"`
`E-W_0=(1)/(2)mv^(2)`
or `v=sqrt((2(E-W_0))/(m))`
`(v_1)/(v_2)=sqrt((1-0.5)/(2.5-0.5))=sqrt((0.5)/(2))=(1)/(2)`