When a high frequency electromagnetic radiation is incident on a metallic surface, electrons are emitted from the surface. Energy of emitted photoelectrons depends only on the frequency of incident electromagnetic radiation and the number of emitted electrons depends only on the intensity of incident light.
Einstein's photoelectric equation correctly explains the PE, where frequency of incident light and work function.
The slope of the graph shown in fig. [here h is the Planck's constant and e is the charge of an electron] is