Two charges `+20 mu C` and `- 20 muC` are 5 mm apart. Find the electric field on axial as well as on the equatorial line at a distance 20 cm from the mid -point of the dipole.

Explanation

Here the distance where electric field is to calculated is very large as compared to the dipole length. So the dipole will be treated as short dipole and formula used will be for `r gt gt g`.
So , electric field on the axial line
`E_(a) = ( 2p)/( 4pi epsilon_(0)r^(3))`
`= ( 9 xx 10^(9)xx2 xx20 xx 10^(-6) xx 5 xx 10^(-3))/((20 xx 10^(-2))^(3))`
`= 2.25 xx 10^(5) N //C`
Electric field on the equatorial line
`E_(a) = ( p)/( 4pi epsilon_(0)r^(3))=(E_(a))/(2)`
`= 1.125xx 10^(5)N //C`