Magnetism Chapter 49

A magnet is a piece of metal that can attract other substances to it. Natural magnets like loadstone are found in nature. Artificial or man made magnets are made by magnetising Iron, Nickel, Cobalt or their alloys.

Like poles Repel-Unlike poles attract Properties of Magnets The magnetic effect of a magnet is strongest at the two ends-called the North and the South pole. The North pole of a freely suspended magnet always points North.. Like poles Repel-Unlike poles attract In this picture will the magnets attract or repel each other?

The North pole of a freely suspended magnet always points North..

Unlike poles repel, Unlike poles attract

A Magnetic field is the space around a magnet where a magnetic force can be seen The magnetic field around a bar magnet can be seen using either Iron filings Plotting compasses

To plot a magnetic field using Iron Filings

To plot the magnetic field of a bar magnet using plotting compasses 1. Place a bar magnet on a sheet of white paper and draw its outline on the paper. 2. Place the compass near the N pole of the magnet. 3. Place a dot on the paper at each end of the arrow of the compass needle. 4.Move the compass . Place its S pole where the N pole was.Mark the point where the needle now points, i.e. Its N pole

Result Magnetic field around the Bar Magnet 5. Repeat step 4 until you reach the other end of the bar magnet. 6. Join the dots in a smooth curve. Repeat the procedure several times Result Magnetic field around the Bar Magnet

The Earth’s Magnetic Field The Earth has a magnetic field as if it had a huge bar magnet at its centre. The South pole of this imaginary bar magnet is near the North Geographical pole.

Uses of Magnets Magnets have various uses. They are used in electric motors, electric bells, bicycle Dynamos, transformers, ammeters, loudspeakers, telephones computers tape recorders,

Electromagnet in use at a scrap yard