1. Electric Circuits containing resistors

2. Circuits Charges travel in a circuit to maintain charge balance

3. Group Work Light the bulb!

4. Light Bulb Anatomy

5. Resistance Current does not flow unhindered Electrical resistance is analogous to friction or drag Expressed as potential needed to maintain a current

6. Circuit Diagrams resistor Potential source

7. Question: Series Circuit Circuit resistance is A. More than with one bulb. B. Less than with one bulb. C. The same as with one bulb. R1R1 R2R2 R3R3

8. Series Circuit Circuit resistance = R 1 + R 2 + R 3 R1R1 R2R2 R3R3

9. Series Summary The same current flows through all resistors in series. The series resistance is the sum of the resistors’ resistances. The resistors’ voltage drops add up to the series total. The voltage drop across a resistor is proportional to its resistance.

10. Question: Parallel Circuit Circuit resistance is A. More than with one bulb. B. Less than with one bulb. C. The same as with one bulb.

11. Parallel Circuit Diagram

12. Potential Differences

13. Currents Total current = I = I 1 + I 2 + I 3 = V/R 1 + V/R 2 + V/R 3 Circuit resistance =V/ I = 1/R 1 + 1/R 2 + 1/R 3 1

14. Parallel Summary The same voltage drops across all resistors in parallel. The series current is the sum of the resistors’ currents. The effective resistance is less than for any individual resistor. Formula is R =

15. Series and Parallel Circuit Circuit resistance = R 1 + 1/R 2 + 1/R 3 1

16. Group Work Determine current direction, current, voltage, and power dissipated for each resistor. 12  6  9  18  9  8  10  3  18  9 

17. Group Work 4.Determine the power for each resistor. 12  6  9  18  9  8  10  3  18  9 