Electrostatic Potential Energy - Practice Questions & MCQ

Electrostatic Potential energy -

It is the amount of work done by external forces in bringing a body from    to a given point against electric force.

or It is defined as negative work done by the electric force in bringing a body from    to that point.

• It is Scalar quantity

• SI Unit: Joule

• Dimension : 

Electric Potential energy at a point

If the point charge Q is producing the electric field

Then electric force on test charge q at a distance r from Q is given by 

   And the amount of work done by the electric force in bringing a test charge from  to r is given by 

                    

    And negative of this work done is equal to electric potential energy

               So 

 electric potential energy 

  distance between two

Change of potential energy-

if a charge q  is moved from   to  in a electric field produced by charge Q

Then Change of potential energy is given as

 

 

 change of energy

 distances

Potential Energy Of System Of two Charge-

 

   where 

   Potential Energy For a system of 3 charges-

Work energy relation-

Where W=work done by an external force

.

The relation between Potential and Potential energy-

As 

But   

So  

Or potential is defined as Potential energy Per unit charge.

i.e 

Where  Potential

 Potential energy

Electron Volt-

=.

It is the smallest practical unit of energy which is used in atomic and nuclear physics.

Electric potential Energy of Uniformly charged sphere-

Where R - Radius and Q - total charge.

Energy density- It is defined as the energy stored for unit volume.

Where  and  .