Types of Magnets

What are the Different Types of Magnets?

by

What are the Different Types of Magnets?

  • Magnetism: The property due to which a substance attracts iron pieces towards it, is called magnetism.
    The substance having property of magnetism, is called magnet.
  • There are two types of magnets: temporary and permanent.
  • Magnets that retain their magnetic properties only for a short period of time are called temporary magnets.
  • Magnets that retain their magnetic properties for a long period of time are called permanent magnets.
  • Temporary magnets are usually made of iron, cobalt, or nickel. These materials behave like magnets only when they are near a strong magnet. They quickly lose their magnetic property if the influence of the strong magnet is removed.
  • Permanent magnets are made from mixtures of iron, cobalt, or nickel with other materials. These make strong magnets and retain their magnetic properties for a long time.

1. Permanent (Natural & Artificial magnets)

Natural magnets: Pieces of naturally occurring iron ore lode–stone or magnetic or black iron oxide (Fe2O3), are called natural magnets.

Properties: These have following two properties.

  1. Attractive property: They attract small iron pieces towards them.
  2. Directive property: When suspended freely, their ends would point in geographical north–south direction. For this reason, the suspended piece is called lode stone or leading stone.

Disadvantages: These have following two demerits:

  1. They have irregular shape.
  2. They are weak.

Artificial  Magnets: These magnets are made of hard steel or special alloys. The substances of these magnets have many small ‘atomic’ magnets. Ordinarily they are all oriented in random directions (Fig.). Then the substance is unmagnetised.
What are the Different Types of Magnets 1
When such a piece is put in North–South direction and hammered, the atomic magnets align themselves in the direction of the earth’s field fig. They retain this alignment and the piece becomes a magnet with North (N) and (S) pole near ends. This magnet with two poles, is called a magnetic dipole.

Advantages: These have following two merits

  1. They may be given desired regular shape.
  2. They are strong.

2. Electromagnets

Electromagnets are based on the magnetic effect of electric current. An electromagnet is usually prepared by placing a soft iron core in a solenoid, or by winding a large number of turns of an insulated wire (generally the insulated copper wire) on a cylindrical soft iron core. An electromagnet shows magnetic properties only as long as the electric current flows through the solenoid. Thus, electromagnets are temporary magnets.

People also ask

What is the difference between a temporary and a permanent magnet?

Electromagnet
Nature of magnetism: Temporary. An electromagnet shows magnetism only as long as current flows through it.
Polarity: The polarity of an electromagnet can be changed by reversing the direction of the current.
Strength: The strength of an electromagnet can be increased or decreased by increasing or decreasing the current.

Permanent magnet (or Bar magnet)
Nature of magnetism: Permanent (or bar) magnets show permanent magnetism.
Polarity: Polarity of a permanent magnet cannot be changed.
Strength: The strength of a permanent magnet cannot be changed.

Poles of a magnet: When ends of a magnet are dipped in iron filings, the filings stick to its ends only and not to its sides. It means that in magnets, centres of attraction are located near ends only. These centres of attraction near the ends of a magnet are called poles.
When this magnet is freely suspended, the two ends point in north–south direction. The pole near the end pointing towards North (north–seeking end) is called North pole. The pole near the end pointing towards South (south–seeking end) is called South pole.
Interaction between poles: The magnetic poles exert forces on each other. Like pole repel each other, i.e., one north pole will repel another north pole or unlike poles attract each other i.e., north pole attract south pole.

Activity

Aim: To make a magnet
Materials needed: A (steel/iron) needle, a magnetic compass, small pins (made of iron) and a bar magnet
Method:

    1. Place the needle on a table.
    2. Rub the magnet along the length of the needle, starting from one end of the needle (end A). When you reach the other end of the needle, lift the magnet and start again at end A.
    3. Repeat the process many times.
    4. Keep the bar magnet away and bring a magnetic compass near the needle. See if it deflects the compass needle. If it does not, repeat Step 2. If it does, your needle has now been magnetized.
    5. Bring the needle close to some iron pins.
      They will be attracted to your newly made magnet.

What are the Different Types of Magnets 1

Observation: The iron pins will get attracted to the needle.

CARE OF MAGNETS
A magnet can lose its properties due to the following activities.

  • Dropping from a height
  • Hitting with a hammer
  • Applying heat
  • Improper storage can also cause loss of magnetic properties.

What are the Different Types of Magnets 2

Bar magnets should be stored in pairs, with Dropping from a height unlike poles alongside each other. A horseshoe magnet should be stored with a piece of soft iron kept across its poles.

Is an electromagnet a temporary or a permanent magnet?

by

Is an electromagnet a temporary or a permanent magnet?

Electromagnets:

  1. A permanent magnet is a magnet that retains its magnetion. A small permanent magnet can be used to hold notes onto the door of a refrigerator. Neodymium magnets are very powerful permenent magnets used in hard drives of computers.
    electromagents
  2. Sometimes we do not want a magnet to stay magnetised all the time. We want it to lose its magnetism so that it can release the object attracted to it. Such magnets are called temporary magnets.
  3. An electromagnet is a temporary magnet. It is made by winding a coil of insulated wire round a soft iron core.
    When a current is passed through the coil, the magnetic field produced by the current magnetises the soft iron core. The soft iron core loses all the magnetism when the current is switched off.
  4. An electromagnet is a temporary magnet which magnetic field is produced by the flow of electric current in a coil wound round a soft iron core.

electromagents 1electromagents 2The electromagnet uses the magnetic effect of an electric current. A wire carrying a current produces a magnetic field in the region around the wire.

People also ask

What are some devices that use electromagnets?

Applications of Electromagnets:

Lifting Electromagnets

Applications of Electromagnets

  1. heavy iron or steel objects such as scrap iron from place to place.
  2. The electromagnet is placed at the end of the cable at the arm of a crane.
  3. It consists of a circular soft iron core and windings made of insulated copper wire.
  4. There are opposite poles on the surface of the electromagnet as shown in Figure. This produces a stronger magnetic field to enable the electromagnet to lift heavier objects.
  5. When the power supply is switched on, the soft iron is magnetised to become a very powerful magnet.
  6. It lifts up iron and steel objects and separate them from non-magnetic objects.
  7. When the crane has moved to a new location, the power supply is switched off and the objects fall off.

Electric Bell

Applications of Electromagnets 1

  1. The electric bell is commonly used in schools as the fire alarm systems.
  2. The electric bell has a very simple but efficient design. There are very few moving parts. A well made electric bell can last for many years.

Electromagnetic Relay

Applications of Electromagnets 2

  1. An electromagnetic relay connects a primary circuit to a secondary circuit.
  2. A small current in the primary circuit will switch on a larger current in the secondary circuit.
  3. A relay is used in the starter system of a car. When the driver turns the key to start the engine, a small current is switched on in the primary circuit.
  4. Figure explains how the relay switches on a larger current in the secondary circuit to operate the starter motor of the car.

Circuit Breaker

Applications of Electromagnets 3

  1. A circuit breaker acts as an automatic switch that breaks open a circuit and switches off the current when the current becomes too large.
  2. In a household circuit, the current may become excessive when there is a short-circuit or an overload.
  3. When the current increases, the strength of the magnetic field of the electromagnet increases suddenly. The soft iron armature is pulled towards the electromagnet, as shown in Figure.
  4. This results in the spring pulling apart the contacts. The circuit is broken and the current flow stops immediately.
    After repairs have been made, the reset button is pushed to switch on the current again.

Telephone Earpiece

Applications of Electromagnets 4

  1. The permanent magnet attracts the magnetic alloy diaphragm with a constant force.
  2. When the caller at the other end of the line talks into the microphone, the earpiece receives a changing current from the telephone line.
  3. The changing current in the coils of the electromagnet changes the strength of the magnetic field. Therefore, the magnitude of the attractive force on the diagram also changes.
  4. This causes the diaphragm to vibrate and reproduce the sound wave from the caller.