Ultraviolet light is incident on two photosenstive materials having work functions `phi_1` and `phi_2 (phi_1 gt phi_2)`. In which case will the K.E. of the emitted electrons be greater ? Why ?

Explanation

Max. K.E. of photoelectron, `K_(max)=hv-phi_0`, As `phi_1 gt phi_2`, so the max. K.E. of the emitted photoelectrons will be greater for the photosenstive material having work function `phi_2`.