A long straight wire of a circular cross-section with radius ' $a$ ' carries a steady current $I$. The…

A long straight wire of a circular cross-section with radius ' $a$ ' carries a steady current $I$. The current I is uniformly distributed across this cross-section. The plot of magnitude of magnetic field B with distance $r$ from the centre of the wire is given by




Solution

We know inside the wire
$\begin{array}{ll}
B=\frac{\mu_0 I}{2 \pi R^2} \cdot r & (O < r < R) \\ \text { And } B=\frac{\mu_0 I}{2 \pi r} & \text { for }(R < r)
\end{array}$

Asked in: JEE Main 2025 (24 Jan Shift 2)

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