Question

Why is minimum or threshold frequency different for different materials?

Answer 1

Some materials have a series of different work functions. This is due to the work function energy of a metal depending on the position of the electron in that metal. The precise shape of the surface of a metal will determine exactly where and how electrons move in the metal. Therefore, the threshold frequency and work function can vary. For example, the work function of silver can range from 3.0 to 4.75 eV.