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(hc + lambda phi))/(m lambda)]^(1//2)`
B. `(2(hc - lambda phi))/(m)`
C. `[(2(hc - lambda phi))/(m lambda)]^(1//2)`
D. `[(2(h lambda - phi))/(m)]^(1//2)`

Answer

B

Explanation

According to Einstein's photoelectric equation
`(hc)/(lambda) = phi + (1)/(2) mv^(2) rArr v = [ (2 (hc - lambda phi))/(m lambda)]^(1//2)`