Bar Magnet Types, Properties and Uses

A bar magnet is an object made out of a permanent magnetic material, such as iron, steel, or any other ferromagnetic substance. It has two poles: the north pole and the south pole, which are located at opposite ends of the magnet. The magnetic field of a bar magnet is strongest at these poles. Questions based on bar magnets have been covered in the NCERT solutions on Magnetism and Matter. 

The following are the properties of a bar magnet that NEET exam aspirants and IISER entrance exam aspirants should know:

1. Every bar magnet has a north and south pole. Like poles repel each other, and opposite poles attract each other.
2. Area around a magnet where magnetic forces can be detected is known as the magnetic field. This field is visualised through magnetic field lines that originate from the north pole and curve around to south pole.
3. A bar magnet is a type of permanent magnet that retains its magnetic properties over time without needing any external magnetic field.
4. Bar magnets are used in experiments to demonstrate the properties of magnetism.

• Rectangular Bar Magnet: This bar magnet is like a rectangular bar with two poles: North and south. 
• Cylinder Bar: This is a cylindrical-shaped magnet which resembles a rod or tube. Just like any other regular magnet, it has a north (N) and South (S) pole at the opposite ends.
• Horseshoe magnet: This type of magnet is shaped like a horseshoe or a U-shape magn

Bar magnets have a number of uses across different fields because of their magnetic properties. Let us understand each one:

• These are used in educational settings for explaining principles of magnetism, including poles, attraction, magnetic fields and repulsion. It makes the knowledge of bar magnets important for CUET exam and IIT JAM exam students.
• Bar magnets are used in a compass to align with Earth's magnetic field. 
• These are used in the construction of simple motors and generators for creating magnetic fields that interact with electric currents.
• Bar magnets are used for separating magnetic fields from non-magnetic ones, such as in recycling plants.
• The principle involved in bar magnets is used in the functioning of MRI machines that use strong magnetic fields for creating images of the inside of the human body.
• Bar magnets are used in magnetic locking systems of doors and cabinets.

• The magnetic field around a bar magnet is visualised through magnetic field lines. These are the imaginary lines that represent the direction and strength of magnetic field.
• The direction of the magnetic field line at any point gives the direction of magnetic field at that point.
• The density of the field lines around a bar magnet indicates the strength of the magnetic field. Closer lines indicate a stronger magnetic field.
• As per the convention, magnetic field lines emerge from the North (N) pole of the bar magnet and curve around to enter South (S) pole.
• Within the magnet, field lines travel from South pole and back to north pole. This completes a closed loop.

Let us take a look at the important questions related to bar magnet: