Physical Science Chapter 8: Magnetism, Motors & Generators

Magnet

An object that produces a magnetic field and attracts certain materials, typically metals like iron.

Magnetic Force

The force exerted by magnets when they attract or repel each other.

Magnetic Field

The region around a magnet where magnetic forces can be detected, represented by field lines.

Magnetic Poles

The regions of a magnet where the magnetic force is strongest; typically labeled as north and south poles.

Compass

An instrument that uses a magnetic needle to indicate direction relative to the Earth's magnetic field.

Domains

Regions within a magnetic material where the magnetic moments of atoms are aligned in the same direction.

Electromagnetism

The interaction between electric currents and magnetic fields, a fundamental principle of physics.

Electromagnet

A type of magnet created by electric current flowing through a coil of wire.

Galvanometer

An instrument used to detect and measure small electric currents by the deflection of a needle.

Commutator

A device in electric motors that reverses the direction of current flow, allowing for continuous rotation.

Electromagnetic Induction

The process by which a changing magnetic field generates an electric current in a conductor.

Turbine

A machine that converts kinetic energy from fluids (like water or air) into mechanical energy.

Transformer

An electrical device that changes the voltage of alternating current (AC) in a circuit.

How to increase the strength of an electromagnet

Increase the current flowing through the wire or add more turns of wire in the coil.

Difference between step-up and step-down transformers

Step-up transformers increase voltage and have more turns on the secondary coil, while step-down transformers decrease voltage and have fewer turns on the secondary coil.

Reason for high voltage transmission

High voltage transmission reduces energy loss over long distances due to lower current.

How Earth acts as a magnet

Earth has a magnetic field generated by the movement of molten iron in its outer core, acting like a giant magnet.

Common magnetic metals

Iron, nickel, and cobalt are the three most common magnetic metals.

How permanent magnets are made

Permanent magnets are made by aligning the magnetic domains of a material through processes like heating and cooling in a magnetic field.

How a simple motor works

A simple motor converts electrical energy into mechanical energy using a rotating coil in a magnetic field.

How a simple generator works

A simple generator converts mechanical energy into electrical energy by rotating a coil within a magnetic field.

Energy sources for power plant generators

Common energy sources include fossil fuels, nuclear energy, wind, solar, and hydroelectric power.

Faraday's contribution

Faraday first identified electromagnetic induction, demonstrating how a changing magnetic field can produce an electric current.

Oersted's contribution

Oersted first identified the relationship between electricity and magnetism, showing that electric currents create magnetic fields.