Practicing Success

Target Exam

CUET

Subject

Physics

Chapter

Moving Charges and Magnetism

Question:

A long wire carrying current I is bent in the form of a circle as shown in the figure.

The $\vec{B}$ at point O is:

Options:

$\frac{\mu_0}{4 \pi} \frac{2 I}{r}(1-\pi)$ perpendicularly outward

$\frac{\mu_0}{4 \pi} \frac{2 \pi I}{r}$ perpendicularly inward

$\frac{\mu_0}{4 \pi} \frac{2 I}{r}(1+\pi)$ perpendicularly outward

$\frac{\mu_0}{4 \pi} \frac{2 I}{r}(1+\pi)$ perpendicularly inward

Correct Answer:

$\frac{\mu_0}{4 \pi} \frac{2 I}{r}(1+\pi)$ perpendicularly inward

Explanation:

Magnetic field due to straight wire is $ B_1 = \frac{\mu_0 I}{2\pi r}$

Magnetic field due to circular wire is $ B_ 2= \frac{\mu_0 I}{2 r}$

$ B = B_1 + B_2 = \frac {\mu_0}{4\pi} \frac{2I}{r}(1+\pi)$ Perpendicularly Inward