Threshold frequency

[jazzchan]

Dear all

The question is :
A certain material has a work function of 0.4eV. What is the energy of a single photon of electromagnetic radiation at the threshold frequency for liberation of photoelectrons?

Would u give me some hint how to find the threshold frequency at first ??

thanks all

jazz

[himanshu121]

Hint : Photoelectric Eqn

[jazzchan]

can i assume the equation is:
K.E = hf - work function = 0 ??

thanks

[Doc Al]

Right. At the threshold frequency the photons have an energy just equal to the work function.