1. Chapter 32
#1-16

2. When drawing circuits, schemes, you must use the accepted symbols for :
Battery
Wire
Resistor
Bulb
Junction
Capacitor
Switch

3. Circuit analysis is based on Σ Iin=Σ Iout
A charge that moves around a looped circuit/path and returns to the starting point has a change in potential of zero.
This idea implies that somewhere in the circuit there is a combination of positive and negative potentials.

4. Hints:
As you go through each circuit element, a change in potential difference (ΔV) is interpreted as:
For an ideal battery, current traveling from negative to positive, potential increases (ΔV = +ε)
For an ideal battery, current traveling from positive to negative, potential decreases (ΔV = -ε)
For a resistor, current traveling from positive to negative, potential decreases (ΔV = -IR)

5. Example:
Lets look at #4 and #43 from pages 992 and 994!!

11. Remember the work kinetic theorem allows us to convert a mass’ motion into work. Therefore,
1/2mv2 = W = qEd = ΔEtherm
And thermal energy depends on the charge through a resistor qΔVR

12. Power in a resistor is equal to the result of current and potential difference of the resistor.
Ultimately this relationship is PR= I2R= I(ΔVR)
Thermal energy dissipated(lost) is the result of time and the power of the resistor (PRt= Etherm)

13. Example #8 from page 993 and #26 from the guided reading:

14. When you buy a battery you are actually purchasing potential.
Real batteries have internal resistance which add to the resistance of the circuit
I=ε/(R+r)

15. The batteries internal resistance causes the battery to loose % potential difference compared to an ideal battery which has no internal resistance.

16. Example:
Compared to an ideal battery, by what percentage does the battery’s internal resistance reduce the potential difference across the 20Ω resistor? (see diagram on board)

17. A battery will “short” if the maximum possible current on the circuit is exceeded.
Short circuit current is found by Isc =ε/r
Shorting out a battery is EXTREMELY dangerous!!!

18. Resistors in parallel…
Have equal potential difference but different current.
Rp = (1/R1 + 1/R2 + 1/R3 +…)-1
Current is still found through I = ε/ΣRp

19. Example #22 and 24 from page 993

20. Mixing resistors in series and parallel takes a bit more thinking/planning:
1.Reduce circuit to the smallest combination of resistace to calculate ΣR so that you can calculate I through the circuit.
2.Work “back” through reduced schematic to solve for ΔV and I in each component.
3.Use table format to summarize calculations.

21. Example #61 from page 996: