Question

A wire $\text{PQ}$ is placed near an infinitely long straight current carrying wire. If both the wires carry the same current and the long wire is kept fixed, which of the following correctly represents the graph of force $F$ vs $x$ ?

• A.
• B.
• C.
• D.

Answer 1

The correct option is D

Let the current flowing through both the wires be $I$ and let $x$ be the distance between the wires as shown in the figure below,



$F=\frac{{\mu }_0{I}^2}{2\pi x}.l_{PQ}$

Here, $F\propto \frac{1}{x}$ as other quantities are constant .

$\therefore$ the graph will be a rectangular hyperbola,

Hence, option $\left(D\right)$ is the correct answer.