Electricity Energy of electrons

Electric Current Electric current = flow of e- To measure current we measure how fast the e- are flowing (e-/second) Current is measured in amperes 1 ampere = 6.25 billion billion electrons / sec Or 1 amp = 1 coulomb / sec ... So….. 1 coulomb of charge = the charge of 6.25 billion billion e-

Resistance = Opposition to the flow of e- Which is a type of opposition to motion so a type of … Friction High resistance can generate…. heat / light Resistance is measured in units called ohms (Ω)

High resistance caused by… Thin wire (filaments) Long wire Insulators (non-metals) High temperature (heat is random motion of mol. While current is motion in one direction)

Voltage = electrical pressure Electrical pressure caused by high concentration of e- Pushes electrons away from high concentration area to area of lower e-conc. Causes current as e- flow away from high pressure Bigger pressure difference causes more voltage and faster current Voltage measured in Volts (V)

Ohm’s Law = relationship among current, voltage and resistance Current is created by differences in e- pressure More pressure difference = more voltage So voltage current Resistance opposes flow so resistance current Current = Voltage I = V Resistance R

Coulomb’s Law The force between 2 charged particles is… directly proportional to amount of charge And inversely proportional to distance squared F = K ( q1q2 / d2 ) Where q = amount of charge and K is a constant

1 coulomb = A unit of charge equal to 6.25 billion billion e- 6.25 x 108 e- Coulombs can be used to measure current because current is rate of flow of e- = flow of charge

Coulomb’s Law applied… If the amount of charge on two particles is doubled….the force of between them Is twice as much If the distance between two particles is doubled…..the force of between them is … ¼ of what it was before

Static Electricity = non flowing e- Static charge can be built up by friction. Rub a balloon on your sweater. Electrons move from the sweater to the balloon The balloon is now negative. Static charge can be built up by induction. Bring the negative balloon near the neutral wall Electrons in the wall sink deeper into the wall to get away from the negative balloon The wall surface is now positive and attracts the balloon by electrostatic force

Induction = charge caused by electrons changing their position within a substance Opposite charged objects attract by Electrostatic force

Series circuits All loads (lights / devices) in single file line connected by sequential wires. Remove one bulb or one wire they all go out Because the circuit is broken/opend

Parallel Circuits Bulbs/loads not in single file line More than one path electrons can take to get to the positive end of the battery. Remove/ turn off one light the rest still light

Circuit Breakers Adding more paths to a circuit reduces resistance Less resistance = _________________ current More current = more friction Circuit breakers break circuit if too much current

Conventional Current Used by Electricians Established before We understood Electrons Its wrong because…

Negative e- flow away from negative end of battery!!!

AC = alternating current e- flow back and forth Electricity from power plant DC = direct current e- flow in same direction all the time like when using a battery