1. Electric Circuits and terms Electric circuits move charges around to deliver energy

2. Electric Circuits Charges move when there is a difference in electric Potential. Electric Potential (think of potential energy) is called electric Voltage Voltage is the driving energy for a circuit and it causes charges to move around. Charges move around and deliver energy (charges are like the tennis balls, these tennis balls (charges) carry energy (volts) which can be delivered to something in the circuit (like a light bulb) The movement or flow of charges is called electric current (coulombs/sec = amps) Current is measured in amps, the symbol for current is I.

3. Electric Circuit Simple circuit

4. Electric Current The amount of electric current depends on the amount of Voltage applied (think of the amount of energy available) and depends on the resistance in the circuit For circuits we often use the analogy of flowing water. Voltage = water pressure, current = flow rate, and resistance is the size of the pipe (or friction in the pipe)

5. Electric circuits Resistance is measured in Ohms. Light bulbs, toasters, hair dryers, etc. and basically just resistors which use up energy. Ohms law : relates how much current flows in a circuit. Ohms law: V = I x R, Voltage = current x resistance.

6. Ohm’s law: V = I x R Example: How much current (I = amps) does a lightbulb (R = 20 ohms) use when connected to 120V (typical voltage in your house)? V = I x R, or I = V/R = 120V/20ohms = 6amps

7. Electric Power Lightbulbs are rated in power units = watts. Power = energy per time. For electric circuits, P = V x I.

8. Summarize circuit terms Voltage: This is the amount of electical energy supplied. Charges carry around energy and transfer this to things like lightbulbs. Current: This is the flow of charges or how many charges flow per second. Measured in Coulombs/sec = Amp (symbol is I) Resistance: A light bulb acts like a resistor which uses up energy Ohm’s law (relates the above 3 terms: V = I R) or Voltage = Current x Resistance.

9. Electric Circuits V(volts) = I(current) x R (resistance) P (power) = V x I = V 2 / R = I 2 x R P = power =energy/time = joules/sec = watts I = current = coulombs/sec = amps R = resistance = ohms V = Volts (energy) = joules/coulomb