Electrostatics
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| Discuss Electrostatics ELECTROSTATICS
COULOMB’S LAW
this law was published by Charles Coulomb in 1785. according to this law, ‘ the force of attraction between two charged particles is given by
F = q1q2/4pe0d2
here e0 is the permittivity of the free space. this force is referred to as the coulomb’s force of electrostatic attraction. the value 1/4pe0 is a dimensional proportionality constant, it is the property of the units used for charge, force and distance concerning the two charges. the value of 1/4pe0 is equal to 9 X 109 N-m2/C2 and the value of is 8.85 X 10-12 C2/N-m. this electric force between two like ( both positive or both negative ) is of a repulsive nature and between two unlike charges, it is attractive in nature. it is because of this reason that like charges repel each other and unlike charges attract each other.
Electric Charge
The unit of electric charge is the coulomb. Ordinary matter is made up of atoms which have positively charged nuclei and negatively charged electrons surrounding them. Charge is quantized as a multiple of the electron or proton charge:
NOTE: The rate of flow of electric charge is called electric current and is measured in amperes.
NOTE: From the precise electrical neutrality of bulk matter as well as from detailed microscopic experiments, we know that the proton and electron have the same magnitude of charge. All charges observed in nature are multiples of these fundamental charges. Although the standard model of the proton depicts it as being made up of fractionally charged particles called quarks, those fractional charges are not observed in isolation always in combinations which produce +/- the electron charge.
An isolated single charge can be called an “electric monopole”. Equal positive and negative charges placed close to each other constitute an electric dipole. Two oppositely directed dipoles close to each other are called an electric quadrupole. You can continue this process to any number of poles, but dipoles and quadrupoles are mentioned here because they find significant application in physical phenomena.
Electric Current
Electric current is the rate of charge flow past a given point in an electric circuit, measured in coulombs/second which is named amperes. In most DC electric circuits, it can be assumed that the resistance to current flow is a constant so that the current in the circuit is related to voltage and resistance by Ohm’s law.
