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

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

Coal Power Plant

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

The U.S. Power Grid

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.

Substation

Transmission Lines

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

Transmission Lines

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.

Transformers

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

Power Grid