[Physics Class Notes] on Uses of Magnets Pdf for Exam

Uses of magnets in daily life can be found in numerous electronic devices, including television, radio, microwaves, hard disks, motors, generators, and many more. 

Magnets are divided into two types: permanent and temporary. The uses of magnets in everyday life vary depending on their type. 

What are Permanent Magnets?

Materials that generate a magnetic field within their internal structure and do not rely on electricity to retain their magnetism are permanent magnets. 

What are Temporary Magnets?

Many materials have the ability to inherit magnetic properties temporarily when in proximity with other magnetic materials, but these fade quickly, returning the material to its original nonmagnetic state. A magnet that loses its magnetic attribute once the permanent magnetic field or electronic current is removed, is a temporary magnet. 

Let’s understand what the practical uses of a magnet in our everyday lives are.

What are the Properties of a Magnet?

Every magnet, irrespective of its size or shape, has two different poles – the north pole and the south pole. The magnetic property of these two poles is more than the rest of the magnet’s body, which means that the magnetic property is maximum in these areas.

Here are three main properties of magnets:

1. Attractive Property: Magnet attracts ferromagnetic materials like iron, nickel, cobalt, among others. Additionally, magnetic poles with opposing magnetic fields attract one another.

2. Repulsive Properties: Property of repulsion and attraction exists between two magnets. Like magnetic poles repel each other. 

3. Directive Property: A magnet, suspended freely, will always point in a north-south direction.

What is the Use of Magnets?

The two types of uses of magnets in daily life are:

• Electromagnets

• Permanent magnets 

Uses of Electromagnets 

Electromagnets are temporary in nature as they only work under the influence of applied electric current. It is made from a coil of wire which behaves as a magnet when an electric current passes through it. An electromagnet is often wrapped around a core magnetic material like steel to enhance the magnetic field produced by the coil.

The strength of the magnetic field of these magnets can be altered by varying the power of the electric current. One can also change its polarity by altering the direction of the electric current. 

For example, the method of magnetic separation is used to separate magnetic substances like steel and iron from waste material. The crane’s long arm is fitted with an electromagnet. When the electromagnet is switched on and the arm is lowered over the heap of waste, the old iron and steel objects present in the waste get attracted to the electromagnet and stick to it. 

Electromagnets are Also Used in the Following: 

1. Generators 

2. Motors

3. Transformers

4. Electric buzzers and bells

5. Headphones

6. Loudspeakers

7. Relays and valves

8. Data storage devices: VCRs, tape recorders, hard discs

9. Induction cooker

10. Magnetic locks

11. MRI machines

12. Particle accelerators

13. Mass spectrometers

We also find the use of electromagnet in other processes like joining two bogies of a train, in a crane (JCB) used to transport heavy materials and waste, and in-service centers and garages to lift heavy vehicles, etc.

The theory of electromagnetism applies to the following domains: 

• Electrostatics

• Magnetic fields of slow and steady currents

• Motional e.m.f. and EMI

• Maxwell’s equations

• The propagation and radiation of EMW

• Electric and magnetic properties of matter

• Laws of conservation

Uses of Permanent Magnets

Permanent magnets are made of materials that inherit the magnetic field, and so the strength of the magnetic field cannot be altered. 

These magnets cannot be demagnetized, unlike electromagnets. 

So its uses can be found in devices like electric motors, magnetic recording and storage media, decorations, among others, where these properties are required. 

For example, a small coil of wire and a permanent magnet inside a speaker transforms the electronic signal to sound vibrations. 

A magnetic compass uses the directive property of the magnet. A compass has a magnetic needle that is pivoted from the center and suspended freely so it can rotate. The needle of the compass when suspended freely will always point in the north-south direction. This compass is used by soldiers, sailors, hikers, etc. 

Magnets are also used to hold objects like box lids, magnetic stickers, the doors of the refrigerator or cupboards, etc.

Permanent Magnets are Used in the Following:

1. Speakers

2. Headphones/earphones

3. Mobile phones

4. Cars

5. Generators

6. Television

7. Transducers

8. Hard drives

9. Sensors

Practical Uses of Magnets

A. Electromagnets

1. Home Appliances

Most of the electric appliances that we use in our homes work on the basic principle of electromagnetism. Some uses of electromagnets in a home include the following:

1. Electric fan

2. Electric doorbell

3. Induction cooker

4. Magnetic locks

So, how is a magnet used in an electric fan and doorbells?

In an electric fan, the EMI keeps the motor rotating, which in turn makes the blades of a fan rotate. 

However, in an electric doorbell, when we press the button, the electromagnetic force of the coil gets energized and the bell makes a sound.

2. Medical Equipment

An MRI or magnetic resonance imaging lets your doctor see the organs, bones, and tissues inside your body without having to do surgery. MRI works on the principle of electromagnetism, employing powerful magnets that produce a strong magnetic field. 

3. Memory Storage Devices 

The data or information in electronic gadgets and phones are stored in the electromagnetic format in the form of bytes and bits. 

4. Computer Hardware

Computer hardware also has a magnetic tape that works on the electromagnetism principle.

5. Communication Devices and Power Circuits

Without electromagnets, the mobile phones we use to communicate with people around the world could not have taken place. The electromagnetic pulses and the interaction of the communication signals make mobile phones and telephones very handy.

6. Others

In devices like electric fans, electric bell, telegraph, debit cards, credit cards, etc.

Did You Know?

In the olden days, electromagnets were mostly used in the data storage of VCP and VCR.

B. Permanent Magnets

There are endless uses of permanent magnets. Some practical uses of the magnet are:

1. Door magnets: Magnets are used to hold objects so they don’t shut on their own, like refrigerators, boxes, and containers, cupboards, etc.

2. Magnetic name tags 

3. Magnetic jewelry

4. Magnetic clasps

5. Magnetic water treatment: A method of passing hard water through a magnetic field to reduce its effects. It is a non-chemical alternative.

6. Magnetic filter

7. Adhesive magnets

8. Magnetic pickup tools

9. Magnetic knife holder

10. Magnetic tray

11. Compass

12. Magnetic toy

13. Maglev train

14. Induction cooker

15. Telephone

16. Cell phone

17. Clocks

18. Scientific instruments

The other three uses of permanent magnets are:

1. Refrigerators

One of the most important uses of permanent magnets is found in closing the door of a refrigerator. The gasket of the refrigerator that seals the door closed, has a thin inner magnetic strip, which is a permanent magnet.

2. Automobiles

Hybrid and electric vehicles use powerful permanent magnets. Magnets used in these automobiles are made of materials with a high proportion of rare earth permanent magnets, which are both expensive and in limited supply. 

3. Jewelry

Jewelry like bracelets, earrings, necklaces, and beads are made of permanent magnets because these magnets help in keeping jewelry clasped closed.

Do You Know?

Permanent magnets are also used in tools like screwdrivers? Screw drivers attract the screws. They are handy when dealing with small screws or hard-to-reach places.