FORM 2-PHYSICS-TOPIC 3-MAGNETISM

Concept of Magnetism

Magnetisation and Demagnetisation

Magnetic Fields of a Magnet

The Concept of Magnetic Fields of a Magnet

Explain the concept of magnetic fields of a magnet

Magnetic field:Is a space surrounding a magnet in which a magnetic force is exerted or experienced. It consists of magnetic field lines which are imaginary lines of force around a magnet from North Pole to South Pole.

The Magnetic Lines of Force around a Magnet using Iron Fillings or Compass Needle

Illustrate the magnetic lines of force around a magnet using iron fillings or compass needle

Experiment.

Aim:To study the properties of magnetic field lines around a bar magnet.

Materials: Iron fillings, bar magnets and a piece of paper.

Procedures

• Place a sheet of plane paper over a bar magnet.
• Sprinkle iron fillings on the sheet of paper.
• Gently tap the sheet of paper.

Observation

• Iron fillings will form a pattern which depends on the magnetic lines of force of the magnet.
• The lines of equal magnetic strength are seen flowing between magnetic poles .The lines are referred to as lines of magnetic flux or field lines. The pattern magnetic force is called a magnetic field.
• When investigating a magnetic field with iron fillings the field is strongest where the fillings are crowded.
• By investigating a magnetic field lines and a bar magnet using a small compass needle, the magnetic flux(lines) runs from north pole to south pole.

Neutral point is a point at which the resultant magnetic flux density is zero.

this area, X, the two magnetic field s cancel or neutralize each other.It happens when two like magnetic poles are brought together.

Therefore neutral point is;

1. an area in a magnetic field where the resultant magnetic field strength is zero.
2. a point which exists where two magnetic field neutralize each other.

The Methods of Magnetic Shielding

Explain the methods of magnetic shielding

Magnetic shielding:Is a screen made from high permeability material used to isolate any material from unwanted magnetic fields

Example; The electron beam in the cathode ray tubes of TV sets, and very delicate measuring instruments are shielded(protected)from magnetic influence by placing them in soft iron cases with thick wells.

Here the object is shielded from the strong magnetic fields by a soft iron ring around it.