Question

A rectangular conducting loop carrying a current ${\text{i}}_{\text{1}}$ is situated near a long straight wire carrying a steady current ${\text{i}}_2$ . The wire is parallel to one of the sides of the loop and is placed in the same plane as that of the loop as shown in the figure. Then, the current loop will

• A. move away from the wire
• B. move towards the wire
• C. remain stationary
• D. rotate about an axis parallel to the wire

Answer 1

Answer: (B)

$F=\frac{{\mu }_0}{2\pi }\frac{i_1{i}_2}{d}l$
where $\text{d}$ is distance between conductors
$\therefore F\propto \frac{1}{d}$

Hence, lesser the distance, more is the force In the given circuit force of attraction is more between $EF$ and $AD$ that of repulsion between $EF$ and $BC$ , hence current loop will move towards the wire.
$F=\frac{{\mu }_0}{2\pi }\frac{i_1{i}_2}{d}l$
$\therefore F\propto \frac{1}{d}$