Thursday, 4 April 2013

Electric Potential

Electric Potential

When a charge is placed at a point in an electric field, some potential energy is associated with its position. The potential energy per unit charge at a point in an electric field is called electric potential at the point.

 , where U is potential energy of the system due to the charge qo in it.

Units: S.I unit is volt (V). 1 volt = 1J/C

Potential Due to a Point Charge
Potential at a point is potential energy per unit charge at that point. Suppose, we want to calculate potential at a distance r from a point charge q.

For this purpose, we place a point charge qo at P. Now potential energy

Potential is a scalar quantity. Therefore, if a large number of charges are present, potential at a given point is simply the scalar addition of potentials due to individual charges.

Potential Difference between Two Points

Consider a point charge qo moved from point A to B. As potential is potential energy per unit charge

Potential at point A or initial potential = 

Potential at point B or final potential = 

  Potential difference between two points is the potential energy difference per unit charge.

Also, U = -WE

Further, if there is no charge in kinetic energy, then WE = -Wext

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