Name: Magnetic Compass
Uploaded: 2019-07-19
Duration: 2 min
Description: What would you need most if you were lost in a desert during the night? Well, some water, a jacket, and most importantly, a magnetic compass to find the dire...

Question

Magnetise a needle using a bar magnet. Make a compass using the magnetised needle.

Accepted Answer

We can magnetise the needle into a small magnet by stroking a bar magnet on it along its length. While stroking, the pole produced at the end where the stroke finishes is the opposite to the stroking pole of the magnet. This means if the stroking pole is the north pole of the bar magnet, the end where the stroking ends will be the south pole of the induced needle. We pass the needle through a cork and make a needle-cork assembly.

The needle-cork assembly is light enough to float on water-filled in the tray. Some detergent is added to the water so that the friction is reduced between the water surface and the surface of the cork. We find that the needle-cork assembly floats in a circular motion for some time. After some time, it gets aligned in a fixed direction. A freely moving magnet always rests in a north-south direction. So, this fixed alignment of the needle-cork assembly is in the north-south direction like any compass. This set up thus can be used as a home-made compass.

Magnetise a needle using a bar magnet. Make a compass using the magnetised needle.

Important Questions on Playing with Magnets

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