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?

Explanation:

Given that,

Chase Q = 80nC = 80×10^-9C

dipole moment p = 1×10^-7 Cm

Distance z = 25cm = 0.25

The Electric field along a dipole moment is given as

E = p / (2π•εo•z³)

We know that k = 1/4π•εo

Then, Electric field becomes

E = 2kp/r³

Where k = 9×10^9 Nm²/C²

Then, the force is given as

F = qE

Therefore,

F = 2k•q•p/r³

F = 2× 9×10^9 ×80×10^-9×1×10^-7/0.25³

F = 9.216 × 10^-3 N