Question

If a copper rod carries a direct current, the magnetic field associated with the current will be?

• A. Parallel to the rod
• B. Perpendicular to the rod
• C. Circular around the rod
• D. No magnetic field

Hint:

Use the right-hand rule to determine the direction of the magnetic field around current-carrying conductors.

Answer 1

The Correct Option is C

When a current flows through a straight conductor, such as a copper rod, a magnetic field is produced around it. 

This is described by Ampere’s Circuital Law, which states: \[ \oint B \cdot dl = \mu_0 I, \] where: \( B \) is the magnetic field, \( \mu_0 \) is the permeability of free space, \( I \) is the current flowing through the conductor. 

The field lines form concentric circles around the conductor, with the direction given by the right-hand rule: Point your thumb in the direction of the current. 

The curl of your fingers gives the direction of the magnetic field.