 # 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. The time for answering the question is over
143 cents In this question, we need to find the magnitude of the electric force on the ball; the answer is   N.

To resolve this question, we're going to need E= that is the magnitude of an electric field in the axis of a dipole at some distance "r" .

where "p" is the magnitude of the electric dipole moment, so in this case p= 1.0  Cm or what is the same cm; and k is a constant k value is =    now to get the force on the ball we need to use F=qE where  so we have  for this, "q" is the charge on the ball, so we got 80nC or what si the same 80× C, and r is the distance between the ball and the dipole, r= 25cm= 0.25m (1m=100cm, so we need to divide 25cm into 100 to get it in meters)

Replacing we got:

F=(80× )(8.99× )(2( )) / and calculating this the answer is   488  