Question

The maximum kinetic energies of photoelectrons emitted from a metal are `k_(1)` and `k_(2)` when it is irradiated with light of wavelenght `lambda_(1)` and `lambda_(2)` respectively. Find work function of the metal.

Answer 1

`K_(1)=(hc)/(lambda_(1))-phi_(0)` or `K_(1)+phi_(0)=(hc)/(lambda_(1))`
and `K_(2)=(hc)/(lambda_(1))-phi_(0)` or `K_(2)+phi_(0)=(hc)/(lambda_(2))`
`therefore (K_(1)+phi_(0))/(K_(2)+phi_(0))=(lambda_(2))/(lamda_(1))`
or `K_(1)lambda_(1)+lambda_(1)phi_(0)=K_(2)lambda_(2)+lambda_(2)phi_(0)`
or `phi_(0)(lambda_(2)-lambda_(1))=K_(1)-K_(2)lambda_(2)` or `phi_(0)(K_(1)lambda_(1)-K_(2)lambda_(2))/(lambda_(2)-lambda_(1))`