Question

An infinitely long wire carrying current $I$ , is bent at right angle as shown in figure. Find the magnetic field at point $\text{P}$ located $x$ distance from $\text{O}$ as shown in the figure.

• A. $\frac{{\mu }_{0}I}{2\pi x}$
• B. $\frac{{\mu }_{0}I}{4\pi x}$
• C. $\frac{{\mu }_{0}I}{2\sqrt{2}\pi x}$
• D. None of these

Answer 1

The correct option is B $\frac{{\mu }_{0}I}{4\pi x}$

Magnetic field due to wire $\text{OA}$ at point $\text{P}$ is zero. Since point $\text{P}$ on the axis of the current carrying wire $\text{OA}$.

Magnetic field due to semi infinite wire $\text{OB}$ at point $\text{P}$

$B_P=\frac{{\mu }_{0}I}{4\pi x}$

$\therefore {\left(B_{\text{net}}\right)}_P=\frac{{\mu }_{0}I}{4\pi x}$

<!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> Hence, option (b) is the correct answer.

Why this question ? Magnetic field due to a straight current carrying conductor along its axis is zero.