Science in Action Notes: Electrical Principles & Tech. (4.0) | Print |


'The Atoms Family' (A Great Electrical Resource Site)
'Just for Kids' (Fun and Games - About Electricity)
'Theatre of Electricity'

4.1 .

Electrical Energy Sources and Alternatives
  65% of electric power is generated by burning fossil fuels (oil, coal, or natural gas).
Using Heat to Generate Electricity

Coal is mined, crushed into a powder, blown into a combustion chamber and burned to release heat. This heat boils water and superheats the resulting steam to a high temperature and pressure, which then turns a turbine. The turbine shaft rotates large electromagnetic coils in the generator to produce electricity.
In a nuclear reactor, atoms of a heavy element, usually uranium, are split (
nuclear fission) in a chain reaction, which releases an enormous amount of energy.
Heat from the Earth's core can also be used to generate electricity. This
geothermal energy (hot water and steam) is channeled through pipes to drive turbines - connected to generators, which produce the electricity.
Biomass is another type of fuel used to generate electricity. The gases produced from the decomposition of garbage in landfills can be used as fuel for stem-driven generators.
Waste heat from many industrial processes is used to produce steam generated electrical power. This process is called

Using Water to Generate electricity
20% of the world's electricity is generated by hydro-electric power plants. Gravitational energy is transformed into electrical energy.

Alternative Energy Sources
- moving water can power turbines, which then run generators. When the tide comes in, the water is trapped in large reservoirs and then allowed to flow out past turbines.
Wind - this energy is harnessed by large propeller-type blades, which turn a shaft - connected to a generator.
Sunlight - Solar cells (made from silicon) enable the energy from the sun to be transformed (photoelectric effect) into electricity.
Batteries - from small portable batteries to rechargeables and most recently to the fuel cells all provide an electrical source by using chemical reactions within the cells.

Renewable and Nonrenewable Energy
Coal is a non-renewable resource (it cannot be replaced, as it is used up). Other fossil fuels are non-renewable as well.
Renewable resources
can be replenished over and over again. These types of resources include; wind energy, solar energy, tidal energy, biomass energy, geothermal energy. Tree harvesting can also be renewed, but it takes a much longer period of time to renew this resource.

4.2 .

Electricity and the Environment

Air pollution
The burning of fossil fuels releases problem substances into the atmosphere.

  • Fly ash, from the burning of coal, is carried up the smokestack and released into the atmosphere.
  • Sulfur Dioxide (SO²) - causes acid rain
  • Nitrogen oxides (NO) - causes air pollution
  • Carbon dioxide (CO²) - is the cause of global warming.

Other Environmental Effects

  • Strip mining techniques removes all plants and animals from large areas of land resulting in habitat and species destruction.
  • Oil and Gas wells can often give off poisonous gases.
  • Steam turbines often release warm water into nearby lakes and rivers. The increase in water temperature can affect the local marine ecology and can kill fish.
  • Mines and refineries that produce nuclear fuel can also cause damage to the environment, because of the radioactive waste.
  • Dams, wind farms and solar cell arrays can desimate large areas of ecological habitat.
  • Tital power plants can disrupt the habitat of fish and other marine life.

Conserving Energy and Nonrenewable Resources
Fossil fuel reserves are decreasing, but with less reliance on these fuels we will be able to see a decrease in pollution. Consering energy can be accomplished a little at a time.

This device helps to calculate the use of electricity in your home and can show you how much money you are using to pay for it. By knowing this, you will likely be motivated to find ways to lower your costs. Finding ways to lower our dependance on fossil fuels and finding alternative fuel sources is a decision that will determine much of what our future environment will be like.

A Sustainable Future
Sustainability means using resources at a rate that can be maintained indefinitely. If sustainability is not achieved, future generations will suffer. A sustainable approach often means a different way of getting what you want. Personal decisions can affect sustainability, even if it seems like its only on a small scale.

4.3 .

Electrical Technology and Society
  Benefits of Electrical Technologies
Electrical technologies have improved our standard of living. Most improvements or inventions have come as a result of a desire to improve speed, efficiency or convenience. This has resulted in freeing up people's time to do other things.

Drawbacks of Electrical Technologies
More technology means more resources are needed to manufacture and operate them, making sustainability more difficult to achieve. As technology advances, obsolete devices become waste, adding to our problems of waste disposal. Some technologies are too expensive for some countries to adopt, leading to isolation and exclusion.

Computers and Information
Computers have revolutionized the way we accomplish many tasks, including writing, calculations and communications. Computers use
binary numbers (0, 1) to store and transmit data which has led to the digital technology era.

Electricity and Computers
Electrical current is used in one way or another in storing or transmitting information. Lasers, photodetectors, and electrical pulses all enable electronic devices to complete the tasks they are made to do.
A computer
hard drive - uses electrical pulses to record and transmit information, by using an aluminum or glass disk, with a thin layer of magnetic material that spins at 300km/h. The electrical pulses are sent to an arm with read and write heads, which are magnetic coils that magnetize spots on the spinning disk.
Reading - magnetic spots induce current in the electomagnetic coil, reproducing 0's and 1's in the original signal and are sent to the computer's processor.
Writing - electrical signals are responded to from the computer's processor.

Electrical Transmission of Information
Electrical signals are sent from computer to computer throughout the world, making the storage and transmission of information compact, easy and relatively cheap. Concerns with this ease is access, privacy and safety. Misleading or false information is also a problem and the 'information explosion' has created other storage, handling and access problems. Search engines help locate some of the information you may be looking for, but they cannot access everything.