Magnetism-

 

Magnetism is a phenomenon associated with the magnetic fields which arise from the motion of electric charges.

 

This motion can take many forms.

• It can be an electric current in a conductor.
• It can be charged particles moving through space.
• It can be the motion of an electron in an atomic model.

 

Types of Magnetism-

 

Magnetism can be divided into two classes-

 

 

1. Pure Magnetism
2. Electromagnetism

 

Pure Magnetism-

 

Pure magnetism deals with iron magnets also called as permanent magnets.

A magnet is a material that creates an invisible field called as magnetic field around itself in which its magnetic effects like-

• attracting other ferromagnetic materials such as iron, nickel, cobalt etc
• and attracting or repelling other magnets can be experienced.

 

 

Until 1820, only this kind of magnetism was known.

 

Electromagnetism-

 

In 1820, a Danish physicist, Hans Christian Oersted while demonstrating the flow of electric current in a wire to his friends noticed that the current causes a nearby compass needle to move.     This image is showing- Oersted (right) and his assistant holding a wire over a compass needle in a north-south direction. The compass needle is then deflected.   Based on the fact that a magnetic needle can be deflected only by a magnetic field, he concluded that- A current carrying wire produces a magnetic field around it.

 

• Electromagnetism is a branch of physics that deals with the study of electricity, magnetism & how they are connected.
• Electromagnetism deals with electromagnets.
• An electromagnet is a temporary magnet that only generates a magnetic field when electric current is flowing through it.
• This makes electromagnets very convenient and controllable since they can easily be turned on or off.

 

Characteristics of Magnetic Field-

 

• Magnetic field is a vector quantity which has both magnitude and direction.
• The SI unit of magnetic field is tesla (T) named after the great scientist Nikola Tesla.
• The CGS unit of magnetic field is gauss (G).
• Other units of magnetic field are NA^-1m^-1 and Wb m^-2. (These units would be derived later)

 

 

Next Article-

Biot-Savart Law

 

Get more notes & other study material of the Chapter Moving Charges & Magnetism.