22Current The flow of electrons through a wire or a conductor. SI unit = (Amps) A
232 types of current A/C – alternating current D/C – direct current ie: by plugging into thehousehold wiringD/C – direct currentie: batteries
24ConductorDEFINITION: Material that allows electrons to move easily through it.IN OTHER WORDS: Just like a train conductor moves cars from one track to another track, conductors move electrons from one place to another.
25Which metal is the best conductor for your internet connection?
27InsulatorDEFINITION: Material that does not allow electrons to move through it.IN OTHER WORDS: Just as a potholder insulates you from heat, electrical insulators slow down or resist the flow of electricity.
41Think of a common household item that has a resistor Something weuse in class?
42Potential Difference - Voltage DEFINTION: Difference in potential between 2 different places.IN OTHER WORDS:It is the amount of work that must be done to carry a charge from one point to another.
43A source of potential difference must keep the current flowing.
44Ohm’s Law Potential difference = current x resistance V (volts) = I (amperes) x R (ohms)Compare to: Water in a HoseElectricity is:DC in a WireElectrical UnitsSymbolpressurepotential (V)VoltsVrate of flowcurrent (I)Amps (or Amperes)Africtionresistance (R)OhmsW
45How do you remember the formula? …..if this helps, use it.
47Practice problems resistance – R = 75 ohms voltage – V = 110 volts A 75 ohm circuit is powered by a 110-Volt energy source. What is the current flowing in this circuit?First we identify the information that we are given in the problem:resistance – R = 75 ohmsvoltage – V = 110 voltsNeed to know amps110V = I x 75 ohms (rearrange formula)Amps = 110 volts / 75 ohms (W)1.5A
48Practice problems resistance = 250 ohms current = 0.95 amps What is the voltage of a circuit with a resistance of 250 ohms and a current of 0.95 amps?First we identify the information that we are given in the problem:resistance = 250 ohmscurrent = 0.95 ampsNeed to know voltsV= 250 ohms x 0.95 ampsVolts = 250 ohms x 0.95 amps237.5V
49Mini Quiz ___ is a flow of electrons thru a wire or conductor. Current A current must have a constant flow of ___CurrentPotential Difference
50Mini Quiz Tendency for a material to oppose the flow of electrons What 3 quantities are related to Ohm’s LawResistanceVoltage, current, and resistance
51Review Quiz of 20.2 before next section View here
65Mini Quiz A _____ is a closed path in which electrons flow Circuit Christmas lights are an example of …..Household wiring are wired by …CircuitSeries CircuitParallel Circuits
66Number your paper 1-9. View here Video quizNumber your paper 1-9.View here
67Check your answers 9. Swimming pool 1. c) electrons Open area Climbing on a metal ladderFishing in a metal boat on a lakeStanding in a field wearing a metal suit1. c) electrons2. a) nucleus3. b) insulators4. c) electrical5. b) attract6. c) positive7. b) neutral8. d) negative