Thursday, 4 April 2013

Electric Field - Electrostatics

When a charged particle placed at a point of space, experiences a force, a field is said to be present in the space. This field which exerts force on a charge is called electric field.

Electric field at a point P near a charged object can be defined as
Where qo is positive point charge (called test charge) and  is the force experienced by it when it is placed at P.

The magnitude of electric field is   , where F = |  |. The direction of electric field is the direction of forced experienced by the test charge.

Thus it follows that when a charge q is placed in electric field, it experiences a force 

Units: SI unit of electric field is N/C. (or V/m)

Electric Field Due to a Point Charge 

A point charge q is placed at O. To define electric field at a point P, we place at test charge qo and find the force acting on it.

Magnitude of electric field  

This direction of electric field is along the line OP away from O.

Electric field vectors due to point charge

Superposition principle 
It states that at a given point, the electric field due to separate charge distributions simply add up vectorially.

We can find the net or resultant electric field due to more than one point charge with the aid to principle of superposition. If we place a test charge qo near n point charges, the net force acting on it is.
     (whereis force on test charge due to ith charge)

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