(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A point charge Q_{1}is distance r from the center of a dipole consisting of charges +/- q_{2}separated by distance s. The charge is located in the plane that bisects the dipole. At this instant, assuming r>> s,

Part A: what is the magnitude of the force on the dipole?

Part B: what is the magnitude of the torque on the dipole?

In the space provided, enter the factor that multiplies (1/ε_{0}) in your answer. Express this factor in terms of q_{2}, Q_{1}, s, π, and r.

2. Relevant equations

1. E_{dipole}=(1/4πε_{0})(2p/r^{3})

2. p=qs

3. F=qE

4. τ=pEsinϑ

3. The attempt at a solution

Part A

Substituting equation 1and 2 into equation 3

F = qE

= (q_{2})(1/4π)(2q_{2}s/r^{3})

Part B

τ = pEsinϑ

= (q_{2}s)(1/4π)(2q_{2}s/r^{3})sin90º

= (q_{2}s)(1/4π)(2q_{2}s/r^{3})

I got a feeling I'm missing an important step involving Q_{1}in both parts.

Help's much appreciated =)

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# Homework Help: Force and Torque on a dipole

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