Electrostatic potential is a scalar quantity measured in joules (J) or electron volts (eV). Equipotential surfaces represent regions in space where the electric potential is constant around a charged body. They are always perpendicular to electric field lines and can be represented by concentric spheres or lines. The relationship between electric field and potential is such that the electric field is defined as the negative gradient of the potential.

1. Chapter -2
Electrostatic Potential

2. Electrostatic Potential Energy

3. It is a scalar quantity. Its SI unit is J (Joule) & electron volt (eV).
1 electron volt is defined as kinetic energy gained or lost by electron in moving through a
potential difference of 1 volt.
1 eV = 1.6 × 10-19J

5. Electric Potential Difference

6. Electric Potential due to single charge

8. Equipotential Surfaces
• Regions in space where electric potential has constant value over a particular
charge distribution is called equipotentials.
• The 3D space in which potential have constant value is called as equipotential
surface & 2D place where potential again has constant value is called as
equipotential lines.
• They are always represented in form of concentric spheres or lines around the
body depending on its dimension.
• These equipotential lines or surface are always drawn perpendicular to that of
electric field lines.
• Some of equipotential surfaces are shown below:-

9. • Equipotential surface due to opposite charges
• Equipotential surface due to similar charges

10. Relation between electric field & electric
potential

11. Electrostatic Potential Energy
• It is defined as minimum work required to be done by external force in moving without
acceleration a test charge q between any two points.
• Consider a system of two charges q1 & q2. suppose q1 is fixed & q2 is moved from point A to B then
•

12. Always remember that while using this expression in numericals sign
present on the charges should be used accordingly.