Nootan Kumar Mittal Class 12th ISC PHYSICS{ Chapter 3rd Electric Potential [part -l ]}

                   Chapter- 3              

            Electric Potential.              

The work done by an external agent in carrying a unit positive test charge from infinity to a point in the electric field is called the electric potential at the point.

	=	electric potential
	=	Coulomb constant
	=	charge
	=	distance of separation

*Electric potential difference (Pd).

"The work done by an external agent in carrying are unit positive test charge from one point to the other point charge in an electric field is called a potential difference between those point"

The charge should be moved very slowly.(no charge in speed or kinetic energy).

-this work is path independent

*. Electric potential due to a point charge.

*.Potential due to an electric dipole

1) axis of dipole.

2)⊥ bisector of dipole.

3) at any point

1). On the axis of dipole

2). On the ⊥ bisector of dipole

3). At any point

*. Relation between E and V .

"Potential always decrease in the direction of field"

Case 1=When electric field is constant.

#. Conceptual question

Case 2=When electric field is non -uniform.

. potential difference with respect of x( y z )-constant.

     Dy=0 , Dz=0.

Conception question.

*.Equipotential surface

Surface on which potential is equal everywhere (3-d)

Example=for a point charge.

V1=V2=V3=V4

"Concentric sheres with charge as centre of  spheres are equal potential surface.

example=. Linear charge

V1 =V2=V3=V4.

*. Property of equipotential surface

1) The potential difference between any two points on equipotential surface is "zero".

2). No no work is done by electric is moving a  charge on equipotential surface.

W electric force=-w external 

3). The direction of electric field is always perpendicular to equipotential surface.

4). Two equipotential surface can never intersect each other.

If they do so, at the point of intersection, there will be two direction of electric field which is impossible.

*. Electric potential energy.

#. Electric potential energy is not  define for single charge.

* EPC of two charger.

#. The electrostatic potential energy of system of a charge is equal work done by external agent in bringing a charge from infinity to that configuration.

#. Conceptual question.

* Potential energy of electric dipole in an electrostatic field.

Fnet= Alway 0

Cases

1).θ=90

2).θ=180°

*Work done in rotation an electric dipole in a uniform.Electric field.

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