Chapter 24, Problem 82A

To determine

The poles of a magnet using a wire and battery.

Explanation of Solution

Introduction:

When electric current flows through a wire, magnetic field is generated around the wire. The direction of the field is determined by Maxwell’s right hand rule. Two magnetic fields interact in such a way that opposite poles attract and vice versa.

When the wire is connected to a battery, it generates a magnetic field around the wire, the direction of the field can be found by Maxwell’s right hand rule. It states that when the thumb points towards the direction of the current the right hand fingers represent the direction of the magnetic field. Therefore, when the wire is connected such that the current flows away and the compass is kept directly above the wire, the field around the magnet will point towards the left. Hence, the arm of the compass pointing right will be the north pole.

Conclusion:

When the wire is connected such that the current flows away, and the compass is kept directly above the wire, the field on the magnet will point towards the left. Hence the arm of the compass pointing right will be the north pole.