# Problem: An electret is similar to a magnet, but rather than being permanently magnetized, it has a permanent electric dipole moment. Suppose a small electret with electric dipole moment 1.0 × 10−7 Cm is 25 cm from a small ball charged to + 80 nC, with the ball on the axis of the electric dipole.What is the magnitude of the electric force on the ball?

###### FREE Expert Solution

Electric force on a charged particle:

$\overline{){\mathbf{F}}{\mathbf{=}}{\mathbf{E}}{\mathbf{q}}}$

Electric field, E, due to a dipole:

$\overline{){\mathbf{E}}{\mathbf{=}}{\mathbf{k}}\frac{\mathbf{2}\mathbf{p}}{{\mathbf{r}}^{\mathbf{3}}}}$

94% (138 ratings) ###### Problem Details

An electret is similar to a magnet, but rather than being permanently magnetized, it has a permanent electric dipole moment. Suppose a small electret with electric dipole moment 1.0 × 10−7 Cm is 25 cm from a small ball charged to + 80 nC, with the ball on the axis of the electric dipole.What is the magnitude of the electric force on the ball?