## Magnetic Field and Magnetic Lines of Force

Subject: Science

#### Overview

The space around a magnet, where magnetic force can be felt by a magnetic body is called magnetic field of that magnet. This note provide us the information of magnetism, neutral point and properties of magnet.

#### Magnetic field

The space around a magnet, where magnetic force can be felt by a magnetic body is called the magnetic field of that magnet. The field can be represented by lines, called magnetic lines of force.

A magnetic line of force is a line, straight or curved, the tangent to which at any point gives the direction of the magnetic field at that point.

Properties of magnetic lines of force:

• Magnetic lines of force start from the North Pole and reach the South Pole externally and then go from the South Pole to the North Pole internally.
• The magnetic lines of force never intersect.
• Magnetic lines of force are crowded near the poles, as the field is strong and are widely separated, where the field is weak.

#### Neutral Point

When two magnetic field i.e. magnetic field of earth's magnet and bar magnet acts in the same place, the resultant field has a special character. When we placed the magnetic needle at any particular point, then the needle does not show any direction at that point as there is no net magnetic field at that point. This point is known as a null point or neutral point.

The given figure A and B show the neutral point. Here, in figure A, when north pole of the magnet points south and magnet in the magnetic meridian, the horizontal component of the earth's magnetic field and bar magnet becomes equal and opposite in point X, which is the neutral point. In figure B, when the north pole of the magnet points geographic north, the neutral point lie towards the lateral side at point X.
A neutral point in a magnetic field is a point at which the horizontal component of earth’s magnetic field and the magnetic field due to the magnet are exactly equal and opposite. At the neutral point, the lines of force will not pass and compass needle will not point in any fixed direction.
In other words, 'A neutral point in a magnetic field is a point at which the horizontal component of earth’s magnetic field and the magnetic field due to the magnet are exactly equal and opposite. At the neutral point, the lines of force will not pass and compass needle will not point in any fixed direction'.

#### Properties of magnet

• A magnet attracts magnetic bodies.
• A freely suspended magnet points north-south direction.
• Like poles of a magnet repel and unlike poles of a magnet attract.
• A magnet has two poles: The North Pole and the South Pole.
• A magnetic material gets magnetized due to the presence of a magnet. It is called magnetic induction.
##### Things to remember
• The space around a magnet, where magnetic force can be felt by a magnetic body is called magnetic field of that magnet.
• A magnetic line of force is a line, straight or curved, the tangent to which at any point gives the direction of the magnetic field at that point.
• A neutral point in a magnetic field is a point at which the horizontal component of earth’s magnetic field and the magnetic field due to magnet are exactly equal and opposite.
• The earth’s magnetism is called terrestrial magnetism
• It includes every relationship which established among the people.
• There can be more than one community in a society. Community smaller than society.
• It is a network of social relationships which cannot see or touched.
• common interests and common objectives are not necessary for society.
##### Questions and Answers

The properties of magnetic lines of force are as follows:

(1) Magnetic lines of force start from the North Pole and reach the South Pole externally and then go from South Pole to North Pole internally.
(2) The magnetic lines of force never intersect.
(3) Magnetic lines of force are crowded near the poles, as the field is strong and are widely separated, where the field is weak.

Properties of magnet are as follows:

(1) A magnet attracts magnetic bodies.
(2)Like poles of magnet repel and unlike poles of magnet attract.
(3)A magnetic material gets magnetized due to presence of a magnet. It is called magnetic induction.
A neutral point is a point in the magnetic field of a magnet placed on the surface of the earth at which the resultant field is zero.

A magnetic line of force is a line, straight or curved, the tangent to which at any point gives the direction of the magnetic field at that point.

The earth's magnetism is called terrestrial magnetism. Declination, dip and horizontal component of earth s magnetic field are elements of terrestrial magnetism which helps to locate correct direction.