Dual Nature of Radiation and Matter
Electron emission is the phenomenon of emission of electrons from the surface of a metal. There are three types of electron emission: thermionic emission, field emission and photoelectric emission.
The photoelectric effect is the emission of electrons from metallic surfaces generally caused by incident light. The famous scientists Hertz, Hallwarch and Lenard investigate the phenomenon of photoelectric emission. Experimental study of photoelectric effect tells about the effect of intensity on photocurrent, effect of potential on photoelectric effect and effect of frequency of incident radiation on stopping potential.
Einstein’s photoelectric equation gives the relation between kinetic energy and frequency of the electrons emit during photoelectric emission. Photoelectric emission can be explained by the particle nature of light (also called photons) and not by wave nature. Photocell is a device whose electrical properties are affected by light and works on the principle of photoelectric effect.
Radiation has dual nature: wave and particle. The nature of experiment determines whether a wave or particle description is best suited for understanding the experimental result. De Broglie attributed a wave like nature to matter or material particles. The waves associated with the particles of a moving material are called matter waves or de Broglie waves. De Broglie wavelength associated with a moving particle is related with the momentum, which is applicable to both the photons of radiation and other material particles.
Davisson and Germer experimentally established the wave nature of slow moving electrons by studying the scattering of electrons.