Question

A current of $10A$ is established in a long wire along positive $z$ -direction. The magnetic field B at the point $(1m,0,0)$ is:-

• A. $1\mu T$ along the $-y$ direction
• B. $2\mu T$ along the $+y$ direction
• C. $1\mu$ T along the $-x$ direction
• D. $2\mu T$ along the $+x$ direction

Answer 1

The correct option is C $1\mu$ T along the $-x$ direction

We know that

$B_i=\frac{{\mu }_{0}I}{2\pi d}$

$=\frac{4\pi \times {10}^{-7}\times 10a}{2\pi \times 1}$

$=2\times {10}^{-6}T$

$=2\pi \mu Tm+y$direction

$\overrightarrow{B}(\overrightarrow{T}\times \overrightarrow{d})$

$=(\hat{z}\times \hat{x})$

$=(\hat{i}\times \hat{i})=\hat{i}m+y$