Grade 9 Academic Science - Electricity

Electricity

Section 12.4

What is Energy?

·  It is difficult to define energy because it comes in many forms. Energy is the ability to do a task.

Electrical Energy is the energy of moving charged particles.

Energy Transformations

·  Energy can be changed from one form to another. For example, a windmill turns wind energy into electrical energy.

All electrical appliances (e.g., TV, refrigerator) use electrical energy. Where does this energy come from?

Making Electricity

·  Most electrical energy is produced by GENERATORS – a machine that converts mechanical energy into electrical energy. The most basic generator is a magnet and a wire coil. Magnets have a North Pole and a South Pole. When the wire rotates past the poles, negatively charged particles in the wire move. The faster the rotation, the more electrical energy generated.

·  Energy in wind, steam or flowing water can be converted into electrical energy. The movement pushed blades of a TURBINE. The turbine is connected to the wire coils inside a generator. When the turbine spins, the coils of the wire generator make electrical energy.

Measuring Electrical Energy

·  All energy, including electrical energy, is measured in JOULES (J).

·  A joule/second is a WATT. The greater the “wattage” of a device, the more electrical energy consumed or used per second. A fluorescent light bulb used 20 J of electrical energy per second. In one minute, the same bulb uses 1200J (20J/s X 60 s).

·  A KILOWATT is 1,000W.

·  A KILOWATT / HOUR is equal to using 1000W in one hour.

For the curious – What is a JOULE?

Approximate value of one joule in everyday life:

·  Energy required to lift a small apple one metre straight up

·  Energy released when that same apple falls one metre to the ground

·  Energy released as heat by a person at rest, every 1/60th of a second

·  Kinetic energy of a 50kg human moving 0.2m/s


Energy Use in Ontario

Ontario’s Energy Consumption

Ontario, Canada’s biggest energy consumer, increased its total energy consumption between 1990 and 2003. Unlike other provinces, Ontario’s growing population has fuelled higher energy demand along with industrial consumption. Despite a 17% upswing in total energy consumption in Ontario, per capita consumption actually declined slightly. This was the result of a higher rate of growth in its population than the increase in energy consumption.

Criteria
2003 Ontario Population / 12,238,300
Per capita energy consumption
(terajoule per person) / 0.26897
Total annual primary energy consumption (terajoules) / 3,291,711
Percent consumption change since 1990 / +17

Source: Marinka Ménard. 2005. Canada, A Big Energy Consumer, A Regional Perspective. Statistics Canada. (online) http://www.statcan.gc.ca/pub/11-621-m/11-621-m2005023-eng.htm#5

Energy Sources in Ontario

Currently electricity is generated in Ontario through hydroelectric (Niagara Falls hydroelectric generator shown), nuclear, coal, gas/oil, wind and biomass. Approximately 73 percentof the electricity generated in Ontario is from nuclear, coal and gas/oil: non-renewable resources with large environmental impacts.

The average Canadian uses approximately 17,000 kWha year, compared to 13,338 kWh forAmericans and 8,468kWh for Europeans.

Source of
Electricity / Amount (MegaWatts) / Percent / Environmental Benefits / Concerns
Hydroelectric / 7,788 / 24 / Renewable
Ecosystem altered
Nuclear / 11,419 / 36 / Non-renewable
Waste
Water for cooling
Coal / 6,434 / 20 / Air pollution including nitrogen oxide (NOX – smog), sulfur dioxide (SOX – acid rain) and carbon dioxide (CO2 – global warming)
Non-renewable
Gas and Oil / 5,703 / 18 / Air pollution
Non-renewable
Wind / 395 / 2 / Renewable
Noise, aesthetics
Biomass / 75 / 0.2 / Renewable
Air Pollution

Source: City of Windsor. (unknown) Energy Consumption Indicator. (online) http://www.citywindsor.ca/003080.asp

Sources of Energy

Energy can be generated from many different sources. Each source has its advantages and disadvantages. As well, each source has a limited potential (e.g., supplies are limited, only available when the wind blows).

Task: Using your textbook, Internet and other sources, complete the following table. An example of the scope and depth of information is provided as a guide.

Type / Source / Obtained / How Energy is Formed / Disadvantages / Advantages / Potential
Wood / Wood / Burning / Burning produces heat to turn water into steam. The steam turns a turbine to produce energy / Gas emissions
Burns trees / Trees are easy to obtain in some parts of the world
Can be small / Limited...will not meet energy needs
Coal
Oil and Gas
Hydro
Nuclear
Solar
Geothermal
Biomass
Wind
Tidal