Question

What are the two ways in which you can trace the magnetic field pattern of a bar magnet?

Answer 1

A bar magnet (or any magnet) will have a north pole and a south pole. The magnetic field lines will start from the north pole and end at the south pole. Since iron is a metal that is magnetic in nature, we can use iron filings or a magnetic compass needle to trace the magnetic field lines of the bar magnet.

Complete step by step solution:
Step 1: Describe the process of tracing the magnetic field lines around a bar magnet using a magnetic compass.

The magnetic compass needle is known to align itself along the geographic north-south direction. So to trace the direction of the magnetic field around a bar magnet we just have to place it at different positions around the bar magnet. The pointer of the compass needle will then indicate the direction of the magnetic field at that position. Now for a position slightly away from the previous position the pointer will align itself so that it points in the direction of the field lines. Marking the pointer on a paper would help to draw the field lines around the bar magnet. The below figure depicts this process.

Step 2: Describe the process of tracing the magnetic field lines around a bar magnet using iron filings.
Another method to trace the magnetic field lines around the bar magnet is to use iron filings. Drop the iron filings around the bar magnet randomly. Since iron is magnetic in nature, the filings will arrange themselves along the direction of the magnetic field lines of the bar magnet. Given below is a rough sketch depicting the arrangement of the iron filings around the bar magnet.

Note: The compass needle can be considered as a bar magnet whose pointer head is the north pole and the tail is the south pole. Since poles repel and unlike poles attract, the tail of the pointer will be facing towards the north pole of the bar magnet while the pointer head will be facing away from the north pole of the bar magnet. The field lines obtained will thus be originating from the north pole of the bar magnet and ending at its south pole.