Saved Bookmarks
| 1. |
Derive an expression for the potential energy of an electric dipole of dipole moment vecp in an electric field vecE. |
|
Answer» Solution :Consider an electric dipole having charges `q_1 = +Q and q_2=-q` located at `vecr_1 and vecr_2`, respectively. Now potential difference between 1 and 2 equals the work done in bringing a unit + ve charge against the electric field from position 2 to 1. `:. V (vecr_1) - V (vecr_2) = -E` (displacement parallel to the field `vecE`). If 2A be the length of electric dipole and dipole be aligned at an angle `theta` from DIRECTION of electric field, then `V(vecr_1) - V (vecr_2) = -E .2 a cos theta` `:.` Potential energy of the dipole in a uniform electric field `vecE` is given by `u = q[ V(vecr_1) - V (vecr_2)] = -E. 2a cos theta = - pE cos theta = - vecp. vecE`. where p = q.2a = dipole MOMENT of the given electric dipole. 
|
|