An electric dipole develops an electric field E at a point P on its axial line. The dipole is turned

Question

An electric dipole develops an electric field E at a point P on its axial line. The dipole is turned through 90$^{\circ}$, then the change of electric field happening at the point P is

Professor PC Thomas Classes · Answer

Initial field on axial line is $E_i$. When rotated 90°, the point is now on the equatorial line with field $E_f = \frac{E_i}{2}$. The change in field is $\Delta E = E_i - \frac{E_i}{2} = \frac{E_i}{2} = \frac{E}{2}$.