A current ` I` flows along the length of an infinitely long, straight , thin - walled pipe. Then

Options

A. The magnetic field at all points inside the pipe is the same but not zero
B. The magnetic field at any point inside the pipe is zero
C. The magnetic field is zero on the axis of the pipe
D. The magnetic field is different at different points inside the pipe

Answer

B

Explanation

Applying Ampere's law `ointB.dl=mu_(0)i` to any closed path inside the pipe we find no current is enclosed hence `B=0`