Question

1 A current flows through an infinitely long straight wire. The magnetic field produced at a point 1 m away from it is

• A. $2\times {10}^{-7}T$
• B. $\frac{2}{10}T$
• C. $2\times {10}^{-3}T$
• D. $2\pi \times {10}^{-6}T$

Answer 1

The correct option is A $2\times {10}^{-7}T$

Current in the wire, l = 1A
Magnetic field due to infinitely long straight wire carrying current l at a distance d (= 1m) from it:
$B=\frac{{\mu }_{0}l}{2\pi d}$
$=\frac{4\pi \times {10}^{-7}}{2\pi }\times \frac{1}{1}$
$=2\times {10}^{-7}T$
Hence, the correct answer is option (1).