A compass is a device that is used to find the direction.
A compass consists of a glass box and a needle with a small pointer-shaped pivoted (rotating) magnet. A compass needle is also known as a plotting compass or a magnetic needle that freely rotates in the horizontal plane inside the glass.
The ends of the needle show the magnetic north and south pole directions, and they approximately point towards the geographic north and south directions.
The north pole needle coloured in red shows the magnetic pole of the earth. It is to differentiate between the magnetic and geographic poles of the earth.
Uses of compass:
- Compass is mainly used in ships and aeroplanes for navigation.
- Mountaineers carry a compass in unknown places to find their way out.
Mountaineer using a compass
Field of influence:
This simple experiment requires some iron filings, a bar magnet, and white paper.
Bar magnet's field of influence
- Collect some iron filings from the sand.
- Spread the filings on white paper and place the paper on the table.
- Place a bar magnet under the sheet kept on the table.
- Now, tap the table gently.
On tapping the table, the iron filings form curved patterns around the magnet. The area surrounding the bar magnet having the iron filings in a pattern showing the magnet's field of influence. This pattern is known as the magnetic field.
The space or field around a magnet where the magnetic effect is observed is known as the magnetic field. The units tesla or gauss measure the magnetic field.
\(1\ tesla\) \(=\) \(10,000\ gauss\)