Electricity and magnetism

William Gilbert

English physician and scientist, published De Magnete in 1600. Summarized everything known about magnetism and electricity at the time.

Electricity

Has positive and negative electric charges.

Like charges repel, and unlike charges attract each other.

Charged objects set up electric field of forces

Certain materials can be electrified through rubbing.
i.e. ebonite rod with cat’s fur

Magnetism

Has north seeking poles and south seeking poles.

Like poles repel, and unlike poles attract.

Magnetic objects set up magnetic fields of forces.

Certain materials can be magnetized through rubbing
i.e. steel rod with lodestone

Magnetic fields

Vector fields that are used to determine the distribution of magnetic force in areas within and around a magnet. They allow magnets to attract objects without touching them.

Domain theory of Magnetism

Every atom ha a magnetic property, each electron in an atom has a magnetic field which is caused by its spin and movements round the nucleus, which causes electrons to act like tiny magnets.

• Ferromagnetic Materials

  Materials STRONGLY attracted to magnets. Iron, nickel, cobalt, chromium dioxide.

• Paramagnetic Materials

  SLIGHTLY attracted by magnets. Iron bearing materials such as aluminum, platinum, manganese, and chromium.

• Diamagnetic Materials

  SLIGHTLY REPELLED by magnets. Bismuth, antimony, copper, zinc, mercury, gold, and silver.

Hans Christian Oersted

Discovered that a magnetic field exists around current-carrying wire. This has established a connection between electricity and magnetism.

BASIC PRINCIPLE OF ELECTROMAGNETISM

• When electrons move through a conductor, a magnetic field is created in the region around the conductor

Generators

An electrical machine that converts mechanical energy into electrical energy.

Uses Electromagnetic Induction, where electrical current is induced through the movement of the magnet or the coil of wire relative to each other.

Motors

An electrical machine that converts electrical energy into mechanical energy.

Uses Electromagnetic Induction, where electrical current is induced through the movement of the magnet or the coil of wire relative to each other.

GEOTHERMAL ENERGY

Magma or hot rocks underneath the Earth’s surface naturally heat ground water, a production well is drilled into the earth in order to bring hot water or steam up, this steam then spins a turbine that powers a generator. Then the steam is cooled and condensed back into water and is injected back into the earth through a second well.

Renewable and sustainable, clean energy, reliable (not dependent on sun or wind)

Specific to locations with strong underground heat, high costs for the wells, environmental concerns if not managed properly, earthquake risks

Earth’s heat → Hot water/steam → Turbine spins → Generator → Electricity