1. General Physics 2Circuits1 Electric Hazards Lethal current - 100 mA causes ventricular fibrillation Larger current - 1 A does not stop heart causes burns Resistance of human body 10 4 - 10 6  when dry 10 3  when wet

2. General Physics 2Current & Resistance2 The Electric Battery Source of voltage or potential difference can make charges move!

3. General Physics 2Current & Resistance3 Battery Model Energy per unit charge delivered by a battery to the charge carriers it transports against the field ξ is the battery’s characteristic emf ξ th is the energy per unit charge lost to thermal energy

4. General Physics 2Current & Resistance4 Battery Model – con’t A chemical battery a chemical reaction to transport charge carriers to the positive electrode

5. General Physics 2Current & Resistance5 Batteries in Series The emf, ξ, of batteries connected in series, adds

6. General Physics 2Current & Resistance6 Electrostatic Potential and the Roller Coaster Analogy The potential is decreasing as it gets closer to the negative plate.

7. General Physics 2Circuits7 Loop Rule

8. General Physics 2Circuits8 DC Circuits – Circuit Symbols Battery Capacitor Resistor Wire Switch Ground

9. General Physics 2Current & Resistance9 Symbol for battery battery resistor

10. General Physics 2Current & Resistance10 Resistors circuit symbol what is the resistance of this resistor? Try some others.

11. General Physics 2Circuits11 Adding Resistors In series: In parallel:

12. General Physics 2Circuits12 Resistance Rank the configurations in order of increasing resistance. SeriesParallel

13. General Physics 2Circuits13 Circuit Elements in Series

14. General Physics 2Current & Resistance14 Calculate Resistance, Current A 12-V battery causes a current of 0.60 A through a resistor. (a) What is its resistance? (b) How many joules of energy does the battery lose in a minute?

15. General Physics 2Circuits15 Loop Rule

16. General Physics 2Circuits16 Resistance, Current, Voltage Determine (a) the equivalent resistance of the circuit, (b) the current through each resistor, and (c) the voltage across each resistor.

17. General Physics 2Circuits17 Circuit Elements in Parallel

18. General Physics 2Circuits18 Consider these two circuits... Series Parallel How does R eq compare between two circuits?

19. General Physics 2Circuits19 Junction Rule

20. General Physics 2Circuits20 Resistance, Voltage Determine (a) the equivalent resistance of the circuit and (b) the voltage across each resistor.

21. General Physics 2 Circuits 21 Rank in order of brightness Rank bulbs 1 through 6 in order of descending brightness. Brightness is proportional to power Now assume the filament in B6 breaks. Again rank the bulbs in order of descending brightness.

22. General Physics 2Circuits22 Practice Problems Determine the equivalent resistance and the current through R 1 for the circuits shown. Assume R 1 = 10 , R 2 = 20 , and R 1 = 30 , and the battery is 12 V.

23. General Physics 2Current & Resistance23 E6 - Activity Exploration of Physics E&M Resistive circuits Do each of the 5 circuits – set all to 50 ohms Calculate I, V, and P for each resistor and then check answers in the program Group Problems E6B.3, E6B.4, E6S.3, E6S.6