Chapter 5

Magnetism

The following Topics and Sub-Topics are covered in this chapter and are available on MSVgo:

Introduction

When you look around yourself, do you see the colourful surroundings that bring you joy? You must have seen many light-emitting devices at your home, like LED bulbs, tube lights and more. So what is light, and how are you able to see things in the light? These questions would be answered in this coming article which talks about light, its properties and some important exam questions based on this chapter.Do you know that the earth is a huge magnet with poles on either side of its diameter? You must have heard that magnets attract iron objects and can also repel other magnets. So how is this possible that a physical substance is capable of attracting and holding other objects with it? What is the history of magnetism? We will answer all these questions in the coming blog.

Magnetism is the phenomenon that is produced by the magnets and mediated by magnetic field lines associated with the magnets. Magnets are physical substances having magnetic properties of attraction and repulsion. There are different types of magnets, including horseshoe magnet, bar magnet, ring magnet, cylindrical magnet and more. 

All these magnets have two poles, namely the North Pole and the South Pole, which attracts and repels objects.

History of Magnet Discovery: There is no solid proof of the discovery, as it is said that a shepherd named Magnes discovered a stone called Magnetite because his iron stick got stuck to that stone

There are two types of substances based on their magnetism.

  • Magnetic Substances: Substances that are attracted to magnets are called magnetic substances. For example, iron, nickel, cobalt, zinc and more.
  • Non-Magnetic Substances: Substances that do not get attracted to magnets are called non-magnetic substances. For example, wood, fibre, glass, rubber and more.

A magnet has some unique properties:

  • Attractive Property: Magnet attracts other ferromagnetic materials such as cobalt, nickel. Also, the unlike poles of magnets attract each other.
  • Repulsive Property: Like poles of magnets repel each other.
  • Directive Property: Freely suspended magnets align themselves in a particular direction that is north-south.

Every magnet forms a magnetic field around them. This can be easily demonstrated by a simple activity as given below.

Place a bar magnet in between a heap of iron filings. The iron filings will arrange into a certain circular direction accumulating at the poles. Hence it is proof that the magnets create a magnetic field around them due to magnetic field lines. The iron filings arrange themselves in the magnetic field lines.

Earth is a huge magnet, and magnetic lines run inside the diameter of the earth. The earth’s north-pole functions as the geometric south-pole and attracts the north pole of a bar magnet and vice-versa. The below activity can demonstrate this.

Take a bar magnet and freely suspend it in the air using a thread tied at the bar magnet’s middle. The bar magnet will suspend itself in the north-south direction, and hence it is proved that the earth behaves as a huge magnet. This property also helps in the manufacturing of a compass that helps in finding direction.

There are two types of magnets.

  • Permanent magnets: These are permanent magnets and hold their magnetic property forever. These permanent magnets are widely used in healthcare equipment like the MRI scan, which uses a large and powerful magnet to diagnose the body.
  • Temporary magnets: These magnets hold their magnetic property only for a short period of time and get demagnetised afterwards. You can make temporary magnets at your home with a simple iron tool.

You can make your own temporary magnet at home using a simple iron piece and a magnet. Check the below activity to make your magnet.

  • Take a rectangular iron bar and put it on the table.
  • Now, using a magnet, rub the iron surface with the magnet by moving the magnet horizontally on its surface.
  • Repeat this process 35-40 times, and afterwards, your iron bar gets magnetised.

Check the following tips to take care of the magnets and use them for a long time.

  • Magnets can lose their magnetic properties if hammered or dropped from high heights. Hence refrain from doing these things.
  • Use an iron case to store magnets not to lose their magnetic properties.
  • Bar magnets should always be stored in pairs.

Magnets are naturally-occurring substances showing magnetism. They are widely used in our daily lives, from gadgets like TVs, stereos to large conveyor belts and more. Substances can be classified as magnetic and non-magnetic substances based on their reaction with magnets. We have many different magnets based on their shapes, stored carefully to keep their magnetic property for a long time.

  1. What are the magnets?
    Magnets are substances that have magnetic properties of attraction and repulsion and are used in daily objects.
  2. What are the different types of magnet based on their shape?
    The different types of magnets based on their shape are bar magnets, horseshoe magnets, oval-shaped magnets, needle-shaped magnets, ring magnets and cylindrical magnets.
  3. Can magnets be demagnetised?
    Yes, magnets can be demagnetised by hammering them, dropping them from large heights, putting them in water and more.
  4. What are magnetic field lines?
    Magnetic field lines are the lines that originate from the magnetic pole and create a magnetic field around the magnet.
  5. What are the applications of magnets?
    The different applications of magnets are in making compass, making seals, earphones, stereos, TVs and more. There are wide industry uses of magnets also that are used in the global manufacturing chain.

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