Presentation on theme: "Electricity and Conserving Resources State Objectives 2.d. and 4.d."— Presentation transcript:
Electricity and Conserving Resources State Objectives 2.d. and 4.d.
What is Electricity? Electricity is a form of energy produced by the flow of electrons from one point to another. Current electricity is a continuous flow of electricity or the amount of a charge that moves past a certain point each second –SI unit for current is the ampere or amp
DC versus AC Current DC current is when the electrical charge moves in one direction –Ex. Batteries Always flow from the negative terminal to the positive terminal. AC current is when the electrical charge flows in one direction, then in the reverse direction over and over again –Ex. Electrical current from the power plant to your home
Controlling a Current Voltage: the measure of how much electrical potential energy each electron can gain (push) –Standard Unit: Volts Resistance: the measure of how difficult it is for electrons to flow through a material (friction) – Standard unit: Ohms –Insulators have a higher resistance than conductors.
Currents Flow In Circuits An electric circuit is a complete path for the flow of electricity –Open circuits have a break in the path –Closed circuits have no breaks in the path
Electric Power Electric power is the rate at which electrical energy is converted into other energy forms (SI unit is the watt) –1 kilowatt= 1,000 watts
Power used be common Appliances AppliancePower (w) Computer350 Color TV200 Stereo250 Refrigerator450 Microwave1,500 Hair Dryer1,000 Which appliance would use the most energy after 15 minutes? A computer or a refrigerator
Generating Electricity Generators are devices that spin a coiled wire within a magnetic field to produce electricity –The mechanical energy of a spinning turbine is transformed into electrical energy for human use. –Primary method for producing the electricity in homes, schools, & the community.
What Spins the Turbine? Energy is produced by burning fossil fuels to boil water produces steam that turns a turbine to generate electricity. –Burning fossil fuels causes a large amount of pollution
Power Grids A power grid is a transmission network that connects power plants to multiple substations near a populated area. –Allows distant energy sources (such as hydroelectric power plants) to be connected to consumers in population centers
Substations A substation is a part of an electrical distribution system that switches, changes, or regulates electric voltage. –transform voltage from high to low, or the reverse. A substation that has a step-up transformer increases the voltage while decreasing the current. A substation that has a step-down transformer decreases the voltage while increasing the current for domestic and commercial distribution.
Transformers Device that transfers electrical energy from one circuit to another & changes the voltage by increasing or decreasing it. –Helps monitor the operation of the power grid and measures current.
Path of Electricity through a Power Grid Power Plant Substation ( there are several along the way) Transmission Lines ( high & low voltage) Transformer (lowers voltage before entering the home) Junction Box on the home (brings it into the home) Outlet (sends it to electrical devices) Electric circuit for a blow dryer
Most energy used by humans comes from fossil fuels. Energy Use
Fossil Fuels Made of hydrocarbons, compounds that contain carbon and hydrogen atoms. Combustion is the process of burning fossil fuels to release energy. –Carbon dioxide and water are two other products of combustion.
Coal Coal is a sedimentary rock formed from dead plant matter that is buried underwater –Solid fossil fuel formed from plant remains. –Makes up about 23 percent of fuel used in the United States. –Most is used for electrical power plants.
Petroleum (Oil) Petroleum (oil) is a mineral made from the remains of dead marine organisms buried in Earth’s crust. –takes hundreds of millions of years to form –Provides one-third of world’s energy. –Can be turned into gasoline, diesel fuel, paints, and plastics.
Alternative Energy Sources Wind power generates electricity by using windmills to turn the blades of a generator.
Alternative Energy Sources Nuclear energy is released when the nuclei of uranium atoms are split apart. This energy is used to produce steam to turn the blades of a generator. Nuclear power does not produce air pollution but does produce radioactive wastes.
Alternative Energy Sources Solar energy is the leading alternative to fossil fuels because it is inexhaustible and produces no pollution. However, it is very expensive. Photovoltaic cells are devices that convert light energy into electric energy.
A pollutant is any substance that contaminates the environment. Examples of air pollutants include smoke, ash, carbon monoxide, and carbon dioxide.
Greenhouse Effect The greenhouse effect is the natural trapping of the Sun’s heat by the Earth’s atmosphere. Gases that contribute to the greenhouse effect include water vapor, carbon dioxide, and methane.
Global Warming As more CO 2 is added, the atmosphere traps more heat, causing global warming.
Effects of Global Warming It changes rainfall patterns. It may increase the amount of storms and hurricanes. It could cause the polar ice caps to melt.
Global Warming Sea-level rise is an increase in sea level that may be caused by global warming. The rise is caused by the expansion of the seawater and by ice that melts and flows into the ocean.
Ozone Depletion The ozone layer of the atmosphere absorbs harmful ultraviolet (UV) radiation from the Sun. Ozone depletion is the thinning of the ozone layer. This allows more UV radiation to reach Earth and could cause an increase in skin cancer.