Question

A long cylindrical wire of radius R carries a uniform current I flowing through it. The variation of magnetic field with distance ‘r’ from the axis of the wire is shown by

• A.
• B.
• C.
• D.

Answer 1

The Correct Option is C

The correct option is (C):
The magnetic field increases as the point moves closer to the boundary of the wire and decreases as it moves away from the boundary of the wire.

Answer 2

For a long cylindrical wire carrying a uniform current, the magnetic field at a distance \( r \) from the axis of the wire increases linearly with \( r \) inside the wire (for \( r < R \)), as given by Ampère's Law. Outside the wire (for \( r > R \)), the magnetic field decreases with \( 1/r \).

Therefore, the correct graph showing the variation of magnetic field \( B \) with distance \( r \) is option (A).