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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
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.
Transmission Lines
• Transmission lines carry electricity from power plants to distribution systems that power commercial and domestic consumers.
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