Magnetism

MAGNETISM

 The term 'magnetic effectvof electric current' means that 'an electric current flowing in a wire produces a magnetic field around it'. In other words, electric current can produce magnetism.

A magnet is an object which attracts pieces of iron, steel, nickel and cobalt.

A bar magnet is a long, rectangular bar of uniform cross-section which attracts pieces of iron, steel, nickel and cobalt.

A magnet has two poles near its ends : North pole and south pole.

North pole ; The end of a freely suspended magnet which points towards the north direction is called north pole of the magnet.

South pole ; The end of a freely suspended magnet which points towards the south direction is called south pole of the magnet.

Magnetic field ; The space surrounding a magnet in which magnetic force is exerted, is called a magnetic field.

The direction of a magnetic field at a point is the direction of the resultant force acting on a hypothetical north pole placed at that point.

Magnetic field lines ; The magnetic field lines are the lines drawn in a magnetic field along which or North magnetic pole would move.

The magnetic field lines always begin from the north pole of a magnet and end on the south pole of the magnet.

Properties of the magnetic field lines;

1. The magnetic field lines originate from the north pole of a magnet and end its south pole.

2. The magnetic field lines comes closer to one another near the poles of a magnet but they are widely separated at other places.

3. The magnetic field lines do not intersect one another.

Magnetic field of Earth 

The earth itself behaves as a magnet. The shape of the earth magnetic field resembles that of an imaginary bar magnet of length one-fifth of Earth diameter buried and its centre.

Magnetic effect of current (or electromagnetism)

Magnetism in human beings

A current flowing in a wire always gives rise to a magnetic field around it.

The two main organs of the human body where the magnetic field produced is quite significant are the heart and the brain.

The magnetism produced inside the human body by the flow of ionic currents forms the basis of a technique called magnetic resonance imaging which is used to obtain images of the internal parts of the body. It is obvious that magnetism has an important use in medical diagnosis because, MRI scans, it in iverse the doctors to see inside the. For example, MRI can detect cancerous tissue inside the body of a person. Please note that the magnetism in human body is actually electromagnetism which is produced by the flow of ionic currents inside the human body. 

Electromagnetic induction : Electricity from magnetism ; The production of electricity from magnetism is called electromagnetic induction.

The process of electromagnetic induction has led to the construction of generators for producing electricity and power stations. The phenomenon of electromagnetic induction was discovered by a British scientist Michael Faraday and an American scientist Joseph Henry independence day in 1831.

A galvanometer is an instrument which can detect to the presence of electric current in a circuit. It is connected in series with the circuit. When no current is flowing through a galvanometer, it's pointer is at the zero mark. When an electric current passes through the galvanometer, then it's pointer deflects either to the left side of the zero mark or to the right side of the zero mark, depending on the direction of current.