Question

The current illustrated in the diagram is directed upward in a straight vertical wire. A compass is placed alongside the wire at the X mark. Which way will the compass point?
- north
- south
- west
- east
The right answer is South. But why? Thank you.

Answer 1

Answer: South

Explanation:

According to the right-hand thumb rule, if the thumb's direction indicates the current, then the wrapping of fingers gives the direction of the magnetic field.

In the given case, magnetic field lines around the wire are in the form of concentric circles. If the compass is placed at x, then the direction of the magnetic field line will be tangential to the concentric circles, which will point toward the south.