(Ch 7.1)

Electric Current—the flow of charges (usually electrons) through a wire or conductor

·      The units of current are Amperes (A)

·      Charges flow from high voltage to low voltage

o    Voltage Difference—the push that causes charges to move (the “electron pump”)

o    The units of voltage difference are Volts (V)

·      For charges to flow, the wire must always be connected in a closed path, a circuit

Sources of electricity:

·      Dry Cell Battery—common batteries

·      Wet Cell Battery—car battery

·      Wall Sockets—generator produces a voltage difference

Resistance—the tendency for a material to oppose the flow of electrons (it changes electrical energy àheat and light)

·      All materials have some resistance

·      The units of resistance are Ohms (Ω)

·      Making wires longer, thinner, or hotter increases resistance

Ohm’s Law—V = IR