Electric Field | Electric Field Intensity | Some Important Points

Electric Field

It is the space around the charge where the electrostatic force of attraction or repulsion can be experienced by any other charge.

  • Its SI unit is N/C.
  • It is a vector quantity.

The electric field produced by the charge Q at point r is given as

                                                                                                                                               - (i)

Force exerted by a charge Q on a charge q is given as

                                                                                                                                                     - (ii)     

Note - Here charge q also exerts an equal and opposite force on the charge Q.

Using equation (¡) in equation (¡¡) we get

F(r) = q E(r)

Electric Field Intensity

It is defined as the force experienced by unit positive charge at that point.

  • Its SI unit is newton per coulomb (N/C).
  • It is also a vector quantity.

Some Important Points

  • Source Charge (Q) - It produces the electric field.    
  • Test Charge (q) - It tests the effect of a source charge. Conventionally, it should be taken as positive.
  • Electric field due to Q is independent of q because Force F is proportional to Charge q, so the ratio F/q does not depend on q.
  • Electric field due to Q is independent on the space coordinate r.
  • Electric field due to positive charge will be directed radially outward from the charge.      
  • Electric field due to a negative charge will be directed radially inwards.
  • The magnitude of the force F on the charge q due to charge Q depends only on the distance r of the charge q from Charge Q.
  • The magnitude of the electric field E will also depend on the distance r.

Comments