1. The Lead Acid Electric Battery + - Spongy Lead (Pb) Lead Oxide (PbO 2 ) Sulfuric Acid Solution H 2 SO 4 Sulfuric Acid Electrolyte: Oxidation at the Negative Plate (Electrode:Anode): Reduction at the Positive Plate (Electrode:Cathode): I Terminals Cell: 2 V Battery: Multiple cells

2. Batteries

3. Kirchoff’s Rules Conservation of charge Junction (Node) Rule: At any junction point, the sum of all currents entering the junction must equal the sum of the currents leaving the junction. Conservation of energy Loop Rule: The some of the changes in potential around any closed path of a circuit must be zero.

4. Energy in a circuit

5. Series Circuit + Apply the Loop Rule

6. Parallel Circuits + Apply the Junction Rule

7. Rule Set – Problem Solving Strategy A resistor transversed in the direction of assumed current is a negative voltage (potential drop) A resistors transversed in the opposite direction of assumed current is a positive voltage (potential rise) A battery transversed from – to + is a positive voltage. A battery transversed from + to - is a negative voltage. Ohm’s Law applies for resistors. Both the loop rule and junction rule are normally required to solve problems.

8. More about the Loop Rule Traveling around the loop from a to b In (a), the resistor is traversed in the direction of the current, the potential across the resistor is – IR In (b), the resistor is traversed in the direction opposite of the current, the potential across the resistor is is + IR

9. Loop Rule, final In (c), the source of emf is traversed in the direction of the emf (from – to +), and the change in the electric potential is +ε In (d), the source of emf is traversed in the direction opposite of the emf (from + to -), and the change in the electric potential is -ε

10. Example Problem 1 Given: Find: current in each resistor V = 3 Volts

11. Example Problem 2 Given: Find: current in the 20  resistor

12. Alternating Current

13. AC Power ?

14. Root Mean Square (rms)

15. The Wheatstone bridge a simple Ohmmeter

16. Charging a capacitor in an RC circuit At t = 0, Q o = 0 and Same Symbol

17. Solving the charging differential equation Kirchoff’s loop rule Convert to a simple equation in Current by taking the first derivative w.r.t. time Separate variables

18. Integrate the results

19. Charge buildup

20. Discharging the capacitor in an RC circuit At t = 0, Q = Q o

21. Solving the discharging differential equation Kirchoff’s loop rule Separate variables Integrate

22. Charge and current decay

24. Electrical Safety Current kills, not voltage (70 mA) Normal body resistance = 10 5  But could be less than 1000  Take advantage of insulators, remove conductors Work with one hand at a time Shipboard is more dangerous Electrical safety is an officer responsibility