Question

Define the following: Thermionic Emission and Dual Nature of Radiation.

Answer 1

Thermionic Emission: The phenomenon of the emission of electrons, from the surface of the metal when it's heated is called thermionic emission. These electrons are called thermions. The number of electrons emitted depends on the temperature at which the metal is heated.
Dual Nature of Radiation: Regarding the nature of light and radiation various theories were up forward. Initially Newton proposed the 'Corpuscular theory', but this was discarded due to some defects. Finally Neils Bohr assumed that light has in fact Dual nature. In some experiments light behaves only as particles, while in some experiments it behaves as wave. In other words, we can say that either the light radiation will behave as particle or wave but not simultaneously. This law is called Bohr's law of comblimentarily of radiation.