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

A point charge q is situated at the origin. A dipolepis placed atr. The angle θ is defined by [itex]\hat{p}\cdot\hat{r}=cos(\theta)[/itex]

Calculate the vector force Fp acting on the dipole by the nonuniform E field of the point charge.

2. Relevant equations

3. The attempt at a solution

I know that the E field of a point charge is 1/4pi e0 * q/r^{2}, and that [itex]F=(p\cdot\nabla)E=\nabla E\cdot p[/itex]

So since the E field of the point charge doesnt rely on phi or theta, i can just say that [itex]\nabla E=\frac{dE}{dr}\hat{r}=\frac{-q}{2\pi\epsilon_{0}r^{3}}\hat{r}[/itex]

Now if I dot that result withp, only the radial portions will remain since [itex]E_{\theta}=E_{\phi}=0[/itex]

All that remains is [itex]\frac{-qp_{r}}{2\pi\epsilon_{0}r^{3}}[/itex]

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# Homework Help: Force on a dipole from a point charge?

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