1. Making Sense of Circuits

2.  How much an object resists electricity flowing  Increasing resistance, lowers the current  Measured in Ohms (Ω)

3.  The combined effect of all resistors  Resistors in series and in parallel act very differently

4.  The resistances of each light bulb combine to form larger resistance = 10Ω 20Ω 100Ω 130Ω

5.  Act all crazy  Follow a weird, hard to spot rule (that kind of makes sense)  When we add a light bulb in parallel, we open up a new route for electrons  So the current out of the battery increases, instead of decreasing like in series

6.  1/R = 1/R 1 + 1/R 2 + 1/R 3 … + 1/R 100000  So if we have 2 bulbs in parallel, each with 10Ω of resistance  1/R = 1/10 + 1/10  1/R = 2/10  1/R = 1/5  R = 5Ω

7. 10Ω 20Ω 60Ω 1/R = 1/10 + 1/20 + 1/60 1/R = 6/60 + 3/60 + 1/60 1/R = 10/60 1/R = 1/6 R = 6Ω (notice the resistance is LESS than when you just had 1 bulb)

8.  Current is the amount of electrons flowing through a conductor, per second  Measured in amperes or Amps (A)  1A = 6.241x10^18 electrons / second

9.  How much “push” there is on electrons  Determines how much energy each electron carries  Determines the current  Voltage is used up by a resistor

10.  A voltage causes a current ◦ The more voltage, the more current  A resistor lessens the current ◦ The more resistance, the less the current I = V/R or V=IR