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What is electromagnetism?

Physics | 7-14 yrs | Interactive

Definition of electromagnetism

Electromagnetism is the type of magnetism produced by an electric current. This phenomenon was discovered in 1819 when a Danish scientist named Hans Oersted noticed the needle on a magnetic compass moved if it was put close to an electric wire.

Before his discovery, scientists believed that electricity and magnetism were two different scientific phenomena. Then, in 1825, an English physicist named William Sturgeon created the first use – able electromagnet that could easily lift a 9 pounds iron piece.

What is an electromagnet?

An electromagnet is a magnet whose magnetic field is created when electricity is flowing. This type of magnet is different from the refrigerator magnets that you use to decorate your refrigerator. A refrigerator magnet is a kind of permanent magnet made of magnetic material that continuously generates a magnetic field. On the other hand, electromagnets are built and produce a magnetic field only when required.

Difference between a permanent magnet and electromagnet?

Permanent magnet

  1. The South – North polarity of a permanent magnet is fixed. It cannot be changed.
  2. Its strength cannot be altered.

Electromagnet

  1. The South – North polarity of an electromagnet can be altered by changing the direction of the current in the coil.
  2. Its strength can be altered by changing the current flowing in it or by changing the number of turns in it.

How is an electromagnet made?

When an electric current flows through a wire, it generates a magnetic field. The magnetic field can be increased by coiling the wire. This allows more current to flow through a smaller distance and increases the magnetic field. The direction of the current determines the direction of the magnetic field.

Right hand rule and electromagnetic field

When electricity flows in a long straight wire it creates a circular or cylindrical magnetic field around the wire according to the right-hand rule, which means the fingers show the direction of the electromagnetic field generated and the thumb points to the direction of flow of electrons or current.

How to make an electromagnet?

Not every material can be used to create an electromagnet. A naturally magnetic material like nickel, cobalt or iron, has to be used. Any of these three materials or their mixtures are used with a solenoid and a battery to create an electromagnet. You too can make your own electromagnet at home by following the given instructions:

Making a simple electromagnet

All of you know that a nail is not a magnet. However, it can be turned into one if you wrap a wire coil, called a solenoid, around it.

Material required –

  • A battery
  • Paper clips
  • Nail
  • Copper wire

3 Steps to make a simple electromagnet

  1. Wrap the copper wire onto the nail. Make sure that the wire-coils are very close and tight.
  2. Wrap the copper wire ends tightly to the top of the battery on both sides where the positive and negative charges are located.
  3. Now, move the contraption on the top of the paper clips that you have. You would be able to easily lift them without touching them. This is electromagnetism at work!

6 Uses of electromagnetism

  1. Electromagnets produce much more powerful magnetic fields than permanent magnets. The power of the electromagnets can be adjusted by changing the amount of current flowing through it. Electromagnets find their uses in many things that we use in our everyday lives.
  2. They are used in cell phones that work on the interaction between the phone signals and magnetic pulses produced by an electromagnet inside the phone.
  3. Electromagnets are also used in magnetic resonance imaging (MRI) machines that help us to look inside the human body.
  4. Loudspeakers use electromagnets to produce sound.
  5. Electromagnets make it easy to handle large chunks of scrap metal via cranes.
  6. Modern generators also require electromagnets to function efficiently.
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