Field Emission

External strong electric field nearer to the surface of the emitter can affect the emission of electrons. A free electron at the extreme surface of the metal can’t escape the surface due to back pull from the positive nuclei in the emitter body. This back pull on a free electron causes a potential barrier on … Read more

Electron Emission

The liberation of electrons from any surface of a substance is called electron emission. Any piece of a metal block consists of plenty of free electrons. Even at room temperature, there are plenty of free electrons moving randomly inside the metallic crystal. Although the free electrons move randomly from one atom to another inside the … Read more

Photoelectric Emission

The free electrons on the surface of the metal body can be emitted by applying light on that surface. When a beam of light strikes on certain metals like potassium, sodium and caesium, electrons can get emitted from those metals. As per quantum physics, light is nothing but a stream of photons. Photons are similar … Read more

Thermionic Emitter

Thermionic Emission When a metal is heated sufficiently, the thermal energy supplied to the free electrons causes the emission of electrons from the metal surface. The electron emission originated by thermal energy is called thermionic emission. At average room temperature, the energy possessed by free electrons in a metal is insufficient to initiate thermionic emission. … Read more

Secondary Emission

When a beam of high-speed electrons or other similar particles strikes on a metal surface, the part of kinetic energy of the moving particles gets transferred to the free electrons on the surface of the metal body. The phenomenon causes electron emission from the surface of the metal body. The Process of electron emission with … Read more

Work Function and Threshold Frequency

Definition of Work Function Work function is defined as the minimum amount of energy required by an electron to escape from a metal surface. Concept of Work Function in Classical Physics The concept of work function is not to hard to understand. Either classical physics or quantum mechanics can explain the concept. As per classical … Read more

Thermionic Emission

All materials are composed of atoms which in turn consists of nucleus, made of protons and neutrons, surrounded by electrons. These electrons are distributed at various levels around the nucleus and thus possess different levels of energy. Now, imagine that we start heating a particular material. The thermal energy so supplied increases the kinetic energy … Read more