If a long hollow copper pipe carriers a direct current, the magnetic field associated with the current will be:

Options

A. Only inside the pipe
B. Only outside the pipe
C. Neither inside nor outside the pipe
D. Both inside and outside the pipe

Answer

A

Explanation

`I_("inside") = 0 , B_("inside") = 0 [As oint B vec(dl) = mu_(0) I]`
Only outside .