Question

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.

Answer 1

Answer:

In this question, we need to find the magnitude of the electric force on the ball; the answer is $9.21$$*$$10^{-3}$N.

Step-by-step explanation:

To resolve this question, we're going to need E=$\frac{k(2p)}{r3 }$ 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$*$$10^{-7}$ Cm or what is the same $10^{-7}$cm; and k is a constant k value is = $k=8.99$$*$$10^{9}$ $\frac{Nm2}{C2}$

now to get the force on the ball we need to use F=qE where $E=$$\frac{k(2p)}{r3 }$

so we have

$F= q*$$\frac{k(2p)}{r3 }$

for this, "q" is the charge on the ball, so we got 80nC or what si the same 80×$10^{-9}$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×$10^{-9}$)(8.99×$10^{9}$)(2($10^{-7}$)) / $(0.25)^{3}$

and calculating this the answer is $9.21$$*$$10^{-3}N$