Question

If the work function for a metal is 1.8 eV, what would be the stopping potential for light having a wavelength of 400 nm? (b) What would be the maximum velocity of the emitted photoelectrons at the metal’s surface? 

Answer 1

a)

$U=\frac Ae=1.8~V,$

b)

$v=\sqrt{\frac{2hc-2A\lambda}{\lambda m}}=678~\frac{km}s.$