The maximum velocity of an electron emitted by light of wavelength `lambda` incident on the surface of a metal of work function `phi`, is
Where h = Planck's constant , m = mass of electron and c = speed of light.

Options

A. `[(2(hlambda-phi))/(m)]^(1//2_`
B. `[(2(hC-lambda phi))/(m lambda)]^(1//2)`
C. `[(2(hC+lambda phi))/(m lambda)]^(1//2)`
D. `(2(hC-lambda phi))/(m)`

Answer

B

Explanation

According to Einstein's photoelectric equation,
`hv=phi+1/2 mv^(2) " " :.(hC)/(lambda)= phi + 1/2 mv^(2)`
`:.((hC)/(lambda)- phi)=1/2 mv^(2) " " :.v^(2)=2/m ((hC)/(lambda)- phi)`
`:.v=[(2(hC-lambda phi))/(m lambda)]^(1//2)`