Physics | VITEEE 2016 | Discussion Page

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

$(\frac{\mu_{0}i}{\pi R^{2}}).r$

$(\frac{2 \mu_{0}i}{\pi R^{2}}).r$

$(\frac{\mu_{0}i}{2 \pi R^{2}}).r$

$(\frac{\mu_{0}i}{2 \pi R^{}}).r$

Option C

Using Ampere's law, we have

$\oint \overrightarrow{B}.\overrightarrow{dl}=\mu_{0}i_{in}$

or $B \times 2\pi r =\mu_{0}\frac{i}{\pi R^{2}}\pi r^{2}$

$\therefore$ $B= \frac{\mu_{0}}{2\pi}.\frac{ir}{R^{2}}$

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