Understanding Electricity, Magnetism, and Electromagnetism
What is Electrical Energy?
Many machines need electrical energy in order to work.
Electrical energy produces changes in matter and can be transformed into other types of energy.
It is transformed into luminous energy in a light bulb.
It is transformed into thermal energy in a vitroceramic hob.
Electrical Charges and Static Electricity
Electricity involves electric charges, which can accumulate in one place or flow from one place to another.
Electric charges can be positive or negative.
Static electricity is an accumulation of an electric charge on the surface of an object.
Have you ever had a small electric shock when you open a door or touch another person?
This is static electricity.
If both objects have the same charges (+ and + or – and -), they repel one another.
If they have different charges (+ and -), they attract each other.
What is Electric Current?
Electric current is the flow of electrical charges through objects.
Currents only flow between objects with different charges.
They flow from positive to negative.
How Does Electric Current Flow?
For electric current to flow, the current must be able to move between objects. How well the electric current flows depends on the type of materials the objects are made of.
What is a Conductor?
A conductor is something that allows an electric current to flow through it. Most metals are good conductors.
Other materials, and even liquids, can also be good conductors, such as lemon juice and potatoes.
What is an Insulator?
An insulator doesn’t allow an electric current to flow through it.
Some materials that are insulators include wood, plastic, rubber, and glass.
Effects of Electricity
There are four main effects of electricity on materials: heat, light, chemical reactions, and magnetic fields.
Electrical Circuits
- Generator: Transforms different types of energy into electrical energy and produces an electric current.
- Conductor: Transports an electric current around the circuit.
- Switch: Turns an electric current on or off.
- Receptor: Uses the electrical energy that flows to it along the conducting wires.
Magnetism
Magnetism is a specific property of materials that contain metallic elements.
Magnets
Some magnets are made from a natural material called magnetite.
All magnets have two opposite poles (north and south).
Magnetic Field
The influence of a magnet in the space around it is called the magnetic field.
Earth’s Magnetism
There is a mixture of iron and nickel at the center of Earth.
Compasses
Compasses have a small magnetic needle. This detects the Earth’s magnetic field.
Electromagnetism
Electromagnetism is when an electric current flows through a conductor and creates a magnetic field around the conductor.
Electromagnets
Electromagnets are temporary magnets. They work when we turn on an electric current, and they stop working when we turn the current off.
How Do We Use Electromagnets?
- Home appliances such as doorbells, where the electromagnet powers an element that vibrates and produces a sound.
- Transport over long distances and at high speed using special trains. These trains can travel very fast because there is very little friction.
- Industrial applications like cranes in recycling centers and junkyards.
- Medical and scientific applications.
Electromagnetic Energy
If we move a magnet through a coil of wire, the magnet’s electromagnetic field generates an electric current in the wire.
Electromagnetic Generator
An electromagnetic generator is a machine that uses magnetism to generate electricity. It has a magnet and a coil that are attached to a rotating rod called an axle. The turning of the axle causes the magnet to move and generates an electric current.
What Was the First Electromagnetic Generator Like?
In 1831, Michael Faraday built the Faraday disc.
The Faraday disc was the first electromagnetic generator.