Question

If a copper rod carries a direct current, the
magnetic field associated with the current will be
(a) only inside the rod
(b) only outside the rod
(c) both inside and outside the rod
(d) neither inside nor outside the rod

Answer 1

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(b) only outside the pipe

If a long hollow copper pipe carries a direct current, the magnetic field associated with the current will be. As the current inside the pipe is zero. Therefore the magnetic field associated with the current will be only outside the pipe.

Answer 2

Answer:

(C) both inside and outside the rod

If the copper rod carries a direct current, the magnetic field associated with the current will be both inside and outside the rod