1. Chapter 6: Electric Energy at Home Unit B: Energy Transformations

2. 6.1 Generating Electric Energy  A generator is a device that makes electricity.  Michael Faraday made the first electric generator in the early 1800s.  Pushing a magnet through a coil of wire generates an electric current, more coils and stronger magnets produce more electric energy.  The large amounts of electricity that we use today are produced by gigantic generators. Input Energy GeneratorKinetic Energy Output EnergyConverter Electric Energy

3. 6.2 Generating and Distributing Electric Energy  Most electricity is made in a generator. Generators contain one or more turbines.  As the blades of the turbines turn, their kinetic energy is transformed into kinetic energy in the generator. This is what produces energy.  See figure 6.5 on Pg 102  Hydro-electric: converts kinetic energy of moving water into electric energy  Thermo-electric: converts chemical energy stored in fossil fuels into thermal energy, then to kinetic energy, then to electric energy  Thermonuclear: splits atoms, releasing thermal energy that is converted to kinetic energy, then to electric energy

4. 6.2 Generating and Distributing Electric Energy (Continued)  Coal-fired thermo-electric plants burn coal to generate electric energy. The smoke from burning the coal is put through scrubbers to remove the harmful chemicals.  See Figure 6.8 on Pg 104  What are the advantages and disadvantages of using fossil fuels like coal, petroleum, and natural gas?

5. 6.2 Generating and Distributing Electric Energy (Continued)  Hydro-electric plants produce much of the electric energy in Canada.  Kinetic energy from falling water is used to generate electric energy  Clean, efficient/little maintenance, little environmental damage, and no emissions  Require large dams which change the ecology of the area

6. 6.2 Generating and Distributing Electric Energy (Continued)  Thermonuclear generation stations split uranium atoms using nuclear fission. This releases a large amount of thermal energy. The energy is then used to make steam and the steam, under pressure, turns a turbine.  See Figure 6.9 on Pg 106  What are the advantages and disadvantages of nuclear energy?

7. 6.2 Generating and Distributing Electric Energy (Continued)  Thermonuclear and thermo-electric plants are sometimes located close to cities. This lessens the distance to transmit the power, but creates environmental issues.  Electricity must be transmitted through power lines to get to the communities they serve. About 10% of the electricity is converted to thermal energy and wasted.  Power lines can also cause problems because heavy storms may cause damage to the power lines and it could take weeks to repair.

8. 6.3 Electric Energy and Power  Energy is the ability to do work.  Work is defined by force (F) multiplied by distance (d) over which the force is applied.  Work = F × d  The joule is the unit used in measuring work.  Force is measured in newtons.  When a newton of force is applied for one meter of distance (1 N × m), one joule of work is done.  Power is the rate at which energy is transferred. Power tells how fast energy is used or produced.  If a machine useds one watt of power, it uses one joule of energy in one second.

9. 6.3 Electric Energy and Power (Continued)  The consumption of electric energy is measured in watts. The watts are multipled by the time it takes to use them.  Energy = power × time  1 watt hour (W×h) = 1 watt × hour  The watt hour is a small unit of energy. Electiric utility companies use a unit of energy 1000 times larger.  One kilowatt hour is equal to 1000 watt hour  kW×h

10. 6.4 Efficiency and Saving Energy  Incandescent light bulbs produce light when electricity flowing through the filament makes the thin wire white hot.  Efficiency is a measure of how completely input energy is converted to accomplish the desired output energy.  Incandescent light bulbs produce more heat than flourescent bulbs, so flourescent bulbs are more efficent. Percent efficiency of an electric device = useful energy output × 100 total electric enrgy input

11. 6.4 Efficiency and Saving Energy (Continued)  Efficiency is important to you and the environment.  You: Use less electricity, save on your monthly utility bill.  Environment: Electricity is generated by fossil fuels.  As coal burns, it produces carbon dioxide, sulfur dioxide, and nitrous oxide gases. These are released into the atmosphere and harmful emissions.  Carbon dioxide is linked to global climate change.  Sulfur dioxide and nitrous oxides are the primary causes of acid deposition.