In a co-axial straight cable, the central conductor and the outer conductor carry equal currents in opposite directions. The magnetic field is zero.
- inside the outer conductor
- in between the two conductors
- outside the cable
- inside the inner conductor
The Correct Option is C
Solution and Explanation
By applying Ampère's law:
\[ \oint \vec{B} \cdot d\vec{\ell} = \mu_0 i_{\text{enc}} = 0 \]
Since the net enclosed current outside the cable is zero (equal and opposite currents in the central and outer conductors), the magnetic field outside the cable is zero.
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