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AP® Physics C: E & M

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Zero Net Force from Unequal Charges

APPHEM-LPGHYD

A charge of magnitude $\mathit{Q}$ is placed at the origin. A second charge of magnitude $\mathit{-4Q}$ is placed at the position $\mathit{x=d}$ along the x-axis.

Other than infinitely far away, at what position on the x-axis will a positive test charge experience a zero net force?

A

$\mathit{x=-d}$

B

$\mathit{x=-\frac{d}{2}}$

C

$\mathit{x=\frac{d}{2}}$

D

$\mathit{x=\frac{3d}{2}}$

E

At no position other than infinitely far away will the positive test charge experience zero net force