potential

9
Potential

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Page 1: Potential

Potential

Page 2: Potential

Potential DifferenceThe potential difference between the points A and B is defined as the work done to move a unit charge from point A to point B

Total Work done (W) to move the charge from A to B:

Work done to move unit charge from A to B is potential difference between A and B

…..3

Work done( ) to move the charge for small distance :

….. 1

We know that ….. 2

Eqn.2 in Eqn.1Fig.1

- On which the force is acting

Page 3: Potential

- Potential at a point A - Potential at a point B

Eqn4 ,Eqn.5 in Eqn.3

From Fig.1

….5

…..4We know that

- distance between the charge Q and point A ;

- distance between the charge Q and point B

Page 4: Potential

To find potential (V) at point ‘B’ substitute in Eqn. 1

Potential or Absolute Potential

Potential at any point is defined as the work done to move a unit positive charge from infinite to a that point in an electric field (E)

Potential difference between a point A and B: …...1

- a charge which create the electric field ‘ E ‘

- distance between the charge Q and point A ;

- distance between the charge Q and point B

Page 5: Potential

Relation between Electric field and potential (E and V)

We know that

…………. 1

…………. 2

Compare 1 and 2

Total change (dv )in V(x,y,z) is the sum of partial changes ( ) with respect to x,y,z.

Page 6: Potential

Electric Dipole

The two equal and opposite charges ,which are separated by a small distance, is called electric -dipole or dipole.

Dipole Moment(M)

It is defined as the product of charge(Q) and distance (d)between the charges

Page 7: Potential

Potential and Electric field intensity due to an electric dipole

The potential at point ‘P’ is the sum of potential due to individual charges at that point

- distance between charge and point ‘P’

- distance between charge and point ‘P’

Consider a positive and negative point charges separated by a distance ‘d’.Position of the charges and are (0,0,d/2) and (0,0,-d/2) respectively.

Page 8: Potential

If the point is far away from the charges the difference between and is negligible.

This approximation may not be made in the numerator

In spherical co-ordinate system

We know that

……1

……4

Eqn.2 ,Eqn.3 in Eqn.1

……2

……3

……5

……6

……7

……8

Page 9: Potential

……9

Eqn.7,Eqn.8,Eqn.9 in Eqn.6