Photons of wavelength `lambda` are incident on a metal. The most energetic electrons ejected from the metal are bent into a circular arc of radius R by a perpendicular magnetic field having a magnitude B. The work function of the metal is (Where symbols have their usual meanings) -

Options

A. `(hc)/(lambda)-m_(e)+(e^(2)B^(2)R^(2))/(2m_(e))`
B. `(hc)/(lambda)+2m_(e)((eBR)/(2m_(e)))^(2)`
C. `(hc)/(lambda)-m_(e)C^(2)-(e^(2)B^(2)R^(2))/(2m_(e))`
D. `(hc)/(lambda)-2m_(e)((eBR)/(2m_(e)))^(2)`

Answer

D