# CBSE Class 12 Physics Notes Electrostatics – Electric potential

Posted on March 16th, 2018

## CBSE Class 12 Physics Notes Electrostatics – What Is Electric Potential?

Physics Notes for Class 12: An electric potential is the amount of work needed to move a unit positive charge from a reference point to a specific point inside the field without producing any kind of acceleration. That reference point may be Earth or a point at Infinity, although any point beyond the influence of the electric field charge can be used as the reference point.
According to classical electrostatics, an electric potential is a scalar quantity denoted by V, equal to the electric potential energy of any charged particle at any location (measured in joules) divided by the charge of that particle (measured in coulombs). By dividing out the charge on the particle a quotient is obtained that is a property of the electric field itself.
The electric potential at the point specified will be the sum of the electric potential from the
left charge (VL) and the electric potential from the right charge (VR).
V = VL + VR
V = k(+2q)/√((3a)2 +(a)2)  + k(-q)/√(a)2+(a)2
V = 2kq/√10a – kq/√2a
V = ( 2/√10 -1/√2)kq/a
V =-0.0746 kq/a

Notice that since the electric potential is a scalar, calculating the electric potential is often much easier than calculating the electric field.
The electric field and the electric potential are not two independent fields. They are two independent ways of conceptualizing the effect that an electric charge has on the space surrounding it. Just as problems in mechanics can be analyzed using a force-approach or an energy-approach, problems dealing with electrical phenomenon can be analyzed by focusing on the electric field or on the electric potential.
Additionally, just as it is sometimes necessary in mechanics to transfer between force and energy representations, it is sometimes necessary to transfer between the electric field and electric potential representations. The relationship between the two fields can be understood by examining the expression of work, which relates force to transfer of energy.

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Electric Potential due to point charge:
The electric potential created by a point charge Q, at a distance r from the charge (relative to the potential at infinity), can be shown to be

VE = 1*Q/4Пε0r.

where ε0 is the dielectric constant (permittivity of vacuum). This is known as the Coulomb potential.

The electric potential due to a system of point charges is equal to the sum of the point charges’ individual potentials. This fact simplifies calculations significantly since the addition of potential (scalar) fields is much easier than the addition of the electric (vector) fields.

The equation given above for the electric potential (and all the equations used here) are in the forms required by SI units. In some other (less common) systems of units, such as CGS-Gaussian, many of these equations would be altered.

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UNITS FOR ELECTRIC POTENTIAL:

The SI derived unit of electric potential is the volt (in honor of Alessandro Volta), which is why a difference in electric potential between two points is known as voltage. Older units are rarely used today. Variants of the centimetre gram second system of units included a number of different units for electric potential, including the abvolt and the statvolt.

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