The photoelectric cut-off voltage in a certain photoelectric experiment is `1.5 V`. Calculate the maximum kinetic energy.

The photoelectric threshold wavelength of certain material is 6000 overset(@) (A) . Find the maximum kinetic energy of the ejected photelectros in electron-volts if the wavelength of the incident radiation is 4000 overset(@)(A) . (Given h = 6.62 xx 10^- 34 Js and c = 3 xx 108 m//s)