1. Section B2.5 Energy Conversions

2. Energy Conversions
While it may be difficult to define energy, it is easy to define and see energy conversions.
Light bulbs convert electrical energy into light energy.
Car motors convert chemical energy into kinetic energy.

3. Evidences of Energy Conversions
Motion: A soccer ball rolls along the ground because it was kicked.
Change in Position: A painter can paint the ceiling because he used energy to climb the ladder.

4. Evidences continued
Change in shape: A spring will compress or stretch when you squeeze or pull the ends.
Change in temperature: Your hand feels hot when you hold it over a candle flame because heat is being transferred to your hand.

5. Natural Energy Conversions
Energy conversions occur every day in nature - not just in the lab.
Nuclear fusion reactions are converted into light energy in the Sun to keep it burning brightly.
Plants convert this light energy into chemical energy (glucose) by photosynthesis.

6. Industrial Energy Conversions
Power stations are needed world wide to meet our electrical needs.
Hydro-electric stations use water’s potential energy to turn turbines.
Coal stations use chemical energy to boil water in order to turn turbines.

7. Nuclear Energy Conversions
Nuclear fission was first harnessed to create nuclear weapons.
After World War II, it was found useful for generating electricity.
CANDU reactors use Uranium to heat water to generate electricity.
Called thermal power stations

8. Solar Energy Conversions
Solar energy is used by plants to make glucose by photosynthesis.
Humans are making more use of solar energy using solar cells.
Solar cells have no moving parts, only layers of chemicals that produce electricity in sunlight.
See Figure B2.20.

9. Hydrogen Fuel Cells
Considered the ‘new’ battery, but operates more like a motor.
Uses hydrogen as ‘fuel’ and makes electricity from chemical energy. It also produces, as ‘waste’, heat and water - a clean energy source.

10. Hydrogen Fuel Cells
Proven very useful in spacecrafts because the byproducts water and heat supply all of the water and heat needed for the trip

11. Homework Read pages 190 - 195 in the textbook. Answer # 1, 6, 8, 9, 10
on page 195