ELECTRIC CIRCUITS

describe electric circuit

energy source and energy consuming device connected by conducting wires where elecric charges move

electromotive force

maximum potential difference across terminals (but its not a force)

electric current

charge per unit time passing thru surface. perpendicular to motion of charges

one coulomb per second equals

1 ampere

conventional current

standard model for electrical circuit analysis, defining current flow from the positive terminal to the negative terminal

direct current

charges move around circuit, same direction at all times

alternating current

charged move first one way then opposite

resistance

ratio of voltage/current, resists flow of current

ohm's law

v/i is a constant. v/i = r, v = ir

electrical conductors have what level of resistivity

low resistivity

electrical insulators have what level of resistivity

high

resistance for length

p * L/A (p = resisitivity in ohm meter)

how does rheostat vary its resistance

changing length of resistor

electric power formula

p = iv, when theres current as a result of voltage (unit: watt)

series wiring

same current thru each device

parallel wiring

same voltage thru each device

internal resistance

when batteries and generators add resistance to circuit

terminal voltage

actual voltage between terminals of battery

junction rule

total current directed into junction = total current directed out junction

loop rule

in closed circuit loop. total potential rise = total potential drop

table for resistors