Download 17.2 Electric Current and Electrical Energy ELECTRIC CURRENT is

17.2 Electric Current and Electrical Energy
ELECTRIC CURRENT is the rate at which charges pass a given point, this is expressed in
amperes (amps)
When you turn something on an electric field is set up along the wire which allows the free
electrons in the wire to move transferring the energy to the next electron
The current moves quickly however the electrons moves slowly
DIRECT CURRENT the charges flow the same direction
ALTERNATING CURRENT the charges shift directions
VOLTAGE is the potential difference between two points in a circuit
You can think of voltage as the amount of energy released
RESISTANCE is the opposition to the flow of electric charge, it can be thought of as
electrical friction
Good conductors have low resistance
Resistance tends to increase with temperature
Superconductors are materials where the temperature can be dropped so low that there is
hardly any resitance
Cells change chemical or radiant energy into electrical energy (a battery is a cell, not
biological cells)
Cells are made of electrolyte which is a chemical that allows electricity to flow, an
electrode is the part the electricity enters or exits
Wet cells have liquid electrolyte and dry cells have dry or pastelike electrolytes
THERMOCOUPLE converts thermal energy into electrical energy
PHOTOCELLS convert light energy into electrical energy