question_answer

A long straight wire of radius R carries current i. The magnetic field inside the wire at distance r from its centre is expressed as:

A) \[\left( \frac{{{\mu }_{0}}i}{\pi {{R}^{2}}} \right).r\]

B) \[\left( \frac{2{{\mu }_{0}}i}{\pi {{R}^{2}}} \right).r\]

C) \[\left( \frac{{{\mu }_{0}}i}{2\pi {{R}^{2}}} \right).r\]

D) \[\left( \frac{{{\mu }_{0}}i}{2\pi R} \right).r\]