Electric Current/Electrical Energy

Current

• The rate at which charges pass a given point. The higher the current, the greater the number of charges that pass the point each second.

• Measured in Amperes (amps)

2 types of current

• Direct current – charges flow in one direction (charges from batteries)

• Alternating current – charges continually shift from flowing in one direction to flowing in the reverse direction. (home outlets)

Voltage

• The potential difference between 2 points in a circuit.

• Expressed in volts (v).• (Basically, how much energy is needed to get

the charge through the wire) • If an item doesn’t need a lot of electricity to

run, it’s low voltage. If it needs a lot, it’s high voltage.

Resistance

• The opposition to the flow of electric charge.• Resistance is expressed in Ohm’s.• Electrical wiring is very low resistance. Light

bulbs, toaster wire is high resistance.

• The bigger the wire, the less resistance. The colder the wire, the less resistance.

Superconductors

• Certain materials, that if cooled enough, will have a resistance of 0 Ohms.

• Superconductors also repel magnets

Cells

• Change chemical or radiant energy into electrical energy.Contains a mixture of chemicals called an electrolyte, which allow charges to flow.

• Also contains electrodes, which is the part of the cell where charges enter and exit.

• There are 2 kinds of cells – wet cells and dry cells.

Wet/Dry Cells

• Wet Cell Ex: Car battery• Combine the use of acids as the electrolyte,

and metal connectors as electrodes. • Dry Cell Ex: Batteries –• The electrolytes are solid or pastelike

Thermocouples

• Converts thermal energy into electrical energy.

• Thermocouples do not generate a lot of energy

Photocells

• Converts light energy into electrical energy.• When light shines on the photocell, electrons

gain energy to move between atoms. The electrons move through a wire to provide energy to power a device.

• Ex: Solar panel