# Resistance and Ohm’s Law. Current Electricity and Static Electricity Current ElectricityStatic Electricity amount of charge moving through a circuit build.

Post on 23-Dec-2015

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• Slide 1
• Resistance and Ohms Law
• Slide 2
• Current Electricity and Static Electricity Current ElectricityStatic Electricity amount of charge moving through a circuit build up of charged particles in one spot In a conductorIn an insulator Moving ChargeNon-moving Charge What about a battery: Electrical energy does not move through a battery so does this mean it is static: No because the charge will move as soon as you allow it
• Slide 3
• Resistance Resistance: The ability of a substance to slow down the flow of electrons
• Slide 4
• Resistance Resistance: The ability of a substance to slow down the flow of electrons What does this look like: Traffic moving from three lanes to one lane. Cars move fast in three lanes but when they have to merge into one lane their speed slows down
• Slide 5
• Amount of Resistance in different parts of the circuit 1)Wire: electrons move easily through the conducting wire (that is why we use copper for wires) = Almost no energy is lost = Almost no resistance 2) Electric load:
• Slide 6
• Amount of Resistance in different parts of the circuit 1)Wire: electrons move easily through the conducting wire (that is why we use copper for wires) = Almost no energy is lost = Almost no resistance 2) Electric load: Light bulbs and heaters force the electrons to move into a narrow space which slows them down. = Lots of energy is lost as heat or light = high resistance
• Slide 7
• Energy lost in heater or light -
• Slide 8
• Resistance and Current Measurements and (units): Voltage (Potential Energy): measured volts (v) Current: measured in amps (A) Resistance: measured in ohms () OHM`S LAW
• Slide 9
• Resistance and Current Measurements and (units): Voltage (Potential Energy): measured volts (v) Current: measured in amps (A) Resistance: measured in ohms () OHM`S LAW Measuring the amount of current that a given voltage produces Ohm was able to calculate the resistance of a circuit Electrical Resistance=ratio of voltage to current Volts (V):Current (A)
• Slide 10
• Measuring Resistance Using Ohms Law R(resistance) = V (voltage) OR V = IR OR I = V I (Current) R Eg. A 3.0 Volt battery attached to a circuit gives off 0.75A. What is the resistance in this circuit?
• Slide 11
• Measuring Resistance Using Ohms Law R(resistance) = V (voltage) OR V = IR I (Current) Eg. A 3.0 Volt battery attached to a circuit gives off 0.75A. What is the resistance in this circuit? R = V = 3.0V = 4.0 I 0.75A
• Slide 12
• Questions 1)The current through a load in a circuit is 2 A. The potential difference (voltage) across the load is 12V. What is the resistance. R = V/I = 12V/2A =6 2) The resistance of a car headlight is 12 . If there is a current of 3 A through the headlight. Find the voltage across the headlight. V = IR = (3A)(12) =36V 3) A 12.0V potential difference is measured across a load that has a resistance of 6 . What is the current through this load I = V/R = (12.0V)/(6) = 2A
• Slide 13