Energy Unit Various forms of energy and types

Energy Defined as – the ability to do work! Types: Potential = energy waiting to happen Kinetic = energy in motion

Solar Energy Solar energy is used PASSIVELY in many 3 rd world nations for cooking and heating. This is done through KNOWN AS Passive Solar Collection – because there are no external parts the sun is used as is. (ex. your solar cookers) In the US there is often ACTIVE SOLAR COLLECTORS – you see these on rooftops. These used external fans, pumps, etc. to help store and move the heat or to store and then use the light.

Passive Collection Convection - the movement caused within a fluid by the tendency of hotter and therefore less dense material to rise, and colder, denser material to sink under the influence of gravity, which consequently results in transfer of heat. Evaporation - the process of a liquid changing into a gas (ie. heating water = steam) Architectural design – windows on south side, cliffs, etc.

Fossil fuels The world consumes (U.S. primary source of energy) fossil fuels for many uses such as gasoline, coal and natural for electricity. These are NON- renewable energy sources The consumption of fossil fuels has its problems such as global warming, acid rain, and greenhouse effect. For these reasons various alternative energy sources are being used. These alternative are at this time costly and not as effective so are not used extensively.

Generators and Motors Motor parts Field coil – stationary magnetic field Armature – rotating windings to produce electromagnetic induction due to reversing magnetic fields Commutator – used to reverse the direction of current while maintaining electrical contact with the brushes, this while the motor is spinning Brushes – electrical contact to the rotating commutator Battery pack – provides electrical force Any device that uses a battery is of direct current

Electrical Energy DC – Direct Current – flows in one direction only (negative to positive) Ex. batteries AC – Alternating Current – changes direction 60 times per second Ex. Home AC/DC Generators work on the principle of electro-magnetic induction to create electrical power. Transformer – will increase or decrease voltage depending on the purpose

Sources Energy sources can be – Renewable = can be replaced when needed Ex -food, wood Non- renewable = cannot be replaced once used Ex – coal, oil, natural gas, uranium Inexhaustible = will never run out Ex – sun, wind, waves

Currents DC – Direct Current – flows in one direction only (negative to positive) Ex. batteries AC – Alternating Current – changes direction 60 times per second Ex. Home TV = ac remote = dc Transformer - changes the voltage either up or down as needed Up to move electricity across great distances Down – to charge our phones