Question 67 of 276

Figure $A$ and $B$ shown two long straight wires of circular cross-section ( $a$ and $b$ with $a\lt b$ ), carrying current $I$ which is uniformly distributed across the cross-section. The magnitude of magnetic field $B$ varies with radius $r$ and can be represented as:

ABCD

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Answer: (C)

Graph for wire of radius $R$:

As $b\gt a$
${B}_{a}\gt {B}_{b}$
${B}_{a}=\dfrac{{\mu }_{0}i}{2\pi a}$
${B}_{b}=\dfrac{{\mu }_{0}i}{2\pi b}$