10 A current is passing through a very long wire of radius 5 cm. Then the magnetic field at a distance of 2 cm inside from its curved surface is ×10⁻⁵ T.

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Accepted Answer

(4) 2.4. Given: I=10 A in a wire of radius r=5 cm; the point is 2 cm in from the curved surface. Distance from the axis: a=5-2=3 cm=0.03 m, which is less than r, so the point is inside the conductor. Idea: Ampere's law on a circle of radius a encloses only the fraction (a²)/(r²) of the current, giving B=(μ₀Ia)/(2π r²). B=(2×10⁻⁷×10×0.03)/((0.05)²)=(6×10⁻⁸)/(2.5×10⁻³)=2.4×10⁻⁵ T. The blank is in units of 10⁻⁵ T, so the number that belongs there is 2.4.

10 A current is passing through a very long wire of radius 5 cm. Then the magnetic field at a distance of 2 cm inside from its curved surface is ______ ×10⁻⁵ T.

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