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AP® Physics C: E & M

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Moderate

Keeping Force Constant Between two Current-Carrying Wires

APPHEM-WKGEOQ

Two wires carrying equal current $\mathit{I}$ in opposite directions are placed a distance $\mathit{a}$ apart. The wires experience a force $\mathit{F}$ due to the current. The wires are moved to a distance $\mathit{\cfrac{a}{2}}$.

If the current in wire one remains the same, which of the following values of $\mathit{I_{2}}$ would result in the same force $\mathit{F}$ between the wires?

A

$\frac{1}{4}\mathit{I_{2}}$

B

$\frac{1}{2}\mathit{I_{2}}$

C

$\mathit{I_{2}}$

D

$2\mathit{I_{2}}$

E

$4\mathit{I_{2}}$