Electrical Energy (electricity)

What is electricity?

• It is the flow of moving electrons• When electrons flow, it is called an electric

current.

Electric Current• The flow of electric charge• Like charges repel each other, unlike

charges (protons & neutrons) attract each other-static electricity

• Measured in amperes

3 things needed to use an electrical current:

• 1. a path for electrons to move through• 2. a power source (something that is

going to make the electrons move)• 3. something to use the electricity (light

bulb, an appliance, etc.)

Electric Circuit

• A pathway made of wire that electrons flow through

• A circuit has to be in a “circle” to work

• The wires have to go from the power source to the appliance and back again

• Some circuits have a switch that can be turned off and on.• When it is off, it makes a gap in the circuit and the

electrons CANNOT flow.• When it is on, the gap is CLOSED and electrons are able

to move and make the appliance work.• A battery makes the electrons flow from the negative end

to the positive end.

Generator• Power source that produces electrical energy when

something is plugged into an electrical outlet (instead of a battery).

• It converts mechanical energy (energy of motion) into electrical energy.

• How it works:• 1. A loop of wire is rotated within a magnetic field.• 2. This rotation produces an electric field that produces

an electric current to flow.• 3. The current continues to flow as long as the wire is

kept rotating (mechanical energy has to be continuously supplied to the generator).

Generator

• Power Grids• The way electricity travels from a

power plant throughout an area (neighborhood, city)

• How it works:• 1. Electricity is generated at a

power plant by a generator.• 2. Elec. Leaves the generator and

goes to a transmission sub station at the power plant to convert the voltage. Has to SUPER HIGH for long distance transmission.

3. Moves from a transmission grid to a power sub station and into transformers (voltage is decreased for homes, businesses) 4. Electricity moves along power lines and into neighborhoods.

Alternating Current

• Electric current that repeatedly reverses direction, twice each cycle

• Used in homes and businesses • Usually at 60 cycles per second, or hertz

(Hz), in North America

Direct Current

• Electric current whose flow of charge is always in one direction

• Used in batteries and solar panels

AC v DC

• By using transformers, AC power can be changed up to very high voltages for transmission and then changed down again to safer voltages for consumers to use, with comparatively very much less loss of power than DC.