Electromagnetism Fundamentals

The physics of electromagnetism was first studied by Hans Christian Oersted in 1820.

An electric current in a wire can deflect a magnetic compass needle.

The attraction between a magnet and iron is due to an electric force.

James Clerk Maxwell developed the sciences of electricity and magnetism separately.

The two glass rods in Figure 1-a repel each other because they have the same type of electric charge.

The electric charge on the rods is created when they are in contact with silk or fur.

When a glass rod is rubbed with silk, a negative charge appears on the rod.

In most everyday objects, there are more negatively charged particles than positively charged particles.

Excess charge can be gained or lost in humid conditions.

Particles with opposite signs of electrical charge repel each other.

Electromagnetism and Its History

Electromagnetism is the combination of electric and magnetic phenomena, and is at the root of devices such as computers, television, radio, and telecommunications.
The study of electromagnetism began with the early Greek philosophers, who discovered that rubbing amber and bringing it near straw causes the straw to jump to the amber.
The Greek philosophers also discovered that certain stones can attract iron, which is now known to be due to magnetic force.

Electric Charge and Its Properties

Electric charge is an intrinsic property of fundamental particles that make up objects.
There are two types of electric charge: positive and negative, named by Benjamin Franklin.
In most everyday objects, there are equal numbers of negatively and positively charged particles, resulting in a net charge of zero, making the object electrically neutral.
When an object gains or loses negative charge, it becomes either negatively or positively charged, resulting in an excess charge.
Excess charge can be neutralized by water in humid conditions.

Charge Interaction and Conservation

Particles with the same sign of electric charge repel each other, while particles with opposite signs attract each other.
Rubbing a glass rod with silk transfers charge from one body to another, rather than creating it.
The hypothesis of conservation of charge states that charge cannot be created or destroyed, only transferred from one body to another.

Discover the basics of electromagnetism, from its ancient Greek roots to its modern applications in technology. Learn about the combination of electric and magnetic phenomena that power devices like computers and radios.