Question

A horizontal overhead power line carries a current of 90A in east to west direction. Magnitude of magnetic field due to the current 1.5 m below the line is :

• A. $1.2T$
• B. $1.2\times {10}^{-10}T$
• C. $0T$
• D. $1.2\times {10}^{-5}T$

Answer 1

Answer: (D)

$1.2\times {10}^{-5}T$

Magnitude of magnetic field at a distance $r$ due to straight current carrying conductor is given by

$B=\frac{{\mu }_0}{2\pi }\frac{i}{r}$

Given : $i=90$ A and $r=1.5$ m

$B=2\times {10}^{-7}\times \frac{90}{1.5}=1.2\times {10}^{-5}T$