Making Sense of Circuits
How much an object resists electricity flowing Increasing resistance, lowers the current Measured in Ohms (Ω)
The combined effect of all resistors Resistors in series and in parallel act very differently
The resistances of each light bulb combine to form larger resistance = 10Ω 20Ω 100Ω 130Ω
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
1/R = 1/R 1 + 1/R 2 + 1/R 3 … + 1/R 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
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)
Current is the amount of electrons flowing through a conductor, per second Measured in amperes or Amps (A) 1A = 6.241x10^18 electrons / second
How much “push” there is on electrons Determines how much energy each electron carries Determines the current Voltage is used up by a resistor
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