2022-02-20 17:28:39
What is Electrostatics?
Study of stationary electric charges at rest is known as electrostatics. An electroscope is used to detect the charge on a body. Pith ball electroscope is used to detect a charge and to know the nature of the charge. Gold leaf electroscope which was invented by Bennet detects a charge and the nature of the charge and determines the quantity of the charge
Conductors, Insulators, and Semiconductors
A body in which electric charge can easily flow through is called conductor (e.g. metals).
A body in which electric charge cannot flow is called insulator or dielectric. (e.g. glass, wool, rubber, plastic, etc.)
Substances which are intermediate between conductors and insulators are called semiconductors. (e.g. silicon, germanium, etc)
Dielectric Strength: It is the minimum field intensity that should be applied to break down the insulating property of insulator.
Dielectric strength of air = 3 x 106 V/m
Dielectric strength of Teflon = 60 × 106 Vm–1
The maximum charge a sphere can hold depends on the size and dielectric strength of the medium in which the sphere is placed.
The maximum charge density of a sphere of radius ‘R’ in terms of electric intensity E at a distance in free space is Eε0(R/r)2.
When the electric field in the air exceeds its dielectric strength air molecules become ionized and are accelerated by fields and the air becomes conducting.
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