APS, Golconda | Priyanka Gupta

MIND-MAP

NOTES

Magnet

The substances which have the property of attracting small pieces of iron, nickel and cobalt etc. are called magnets and this property of attraction is called magnetism.

Properties of magnet:

Attracts objects of iron, cobalt and nickel.
Force of attraction of a magnet is greater at its poles then in the middle.
Like poles of magnets repel each other while unlike poles of magnets attract each other.
A free suspended magnet always point towards north and south direction.
The pole of a magnet which points toward north direction is called North Pole or north seeking.
The pole of a magnet which points toward south direction is called South Pole or south seeking.

Magnetic field

The space around a magnet in which the force of attraction and repulsion due to the magnet can be detected is called the magnetic field.

IMPORTANT NOTE:- Each point in the field of any magnet has a particular strength and magnetic field at each point has definite direction.
How do you find the direction of the magnetic field due to magnet at a point near it?
The direction of the magnetic field due to a magnet at a point near it can be found by placing a magnetic compass at that point. The compass needle gets deflected when it is placed near the magnet.

Magnetic field lines

Imaginary lines used to represent magnetic field around a conductor/ magnet

Iron filings test around a bar magnet

Iron filings around a bar magnet exhibit the magnetic field lines that engirdle the bar magnet. The magnetic field lines can be explained as imaginary lines that graphically represents the magnetic field that is acting around any magnetic substance.

Properties of magnetic field lines

All field lines are closed curves.
Outside the magnet field lines emerge from North Pole and merge at South Pole.
Inside a magnet, the direction of field lines is from South Pole to its north pole.
Field lines never intersect each other.
Field lines are closed together near the poles and spread out away from them.
The field is stronger where the field lines are more closely spaced. So, the field is stronger near the poles then at other points.

Why do field lines never intersect each other?
If two lines were to intersect each other, then a compass needle placed at the point of interaction would point in two different directions which is not possible.

Magnetic Field Due to a Current Carrying Conductor

Electricity and Magnetism are related phenomenon. When an electric current is passed through metallic conductor, it generates a magnetic field around it.

Magnetic Field due to current through straight Conductor
Electric current through a straight Conductor generates magnetic field around it.
a)Magnetic Field intensity increases on the increasing the current in the conductor
b) Magnetic field decrease as the distance increase from the conductor
c) Magnetic Field direction can be find using Right Hand Thumb Rule

What is Right Hand Thumb rule?
When you are holding a current-carrying straight conductor in your right hand such that the thumb points towards the direction of current. Then your fingers will wrap around the conductor in the direction of the field lines of the magnetic field