1. Day 27 : 9-26-11 Topic: Battery Objective : How do Batteries Work Starter: Recall from your last lab-What 2 electrodes produced the highest voltage?

2. Jigsaw -How Batteries Work Your teacher will assign your sections in the reading. Your group will read, discuss and write down on a whiteboard 3-4 facts per the reading. You will present your facts to the class. Everyone will record the information in their notebook.

3. What is a Battery?

4. History Galvani and Animal Electricity (1791) Frog’s leg contracted when connected to static electricity machine Thought frog was source of electric charge and that wires just completed circuit Volta – skeptical of “life force” Thought frog was just a detection device Knew he had to replace frog with man- made device

5. The Wet Battery The unit of voltage, VOLTS, is named after Alessandro Volta

6. How a Battery Works movie (d21.mov) movie

7. A battery must have… Two electrodes – two rods or plates of different metals - electrodes A solution in which charged ions can travel – electrolyte A container to hold the electrolyte Sometimes, other metal caps are attached to the electrodes - terminals

8. Chemical Reactions Occur in a Battery Some metals – copper, gold, lead give up electrons easily Other metals – zinc, aluminum take up electrons easily Charge is transported from one electrode to the other via a suitable ion from an acid or alkali

9. What a Battery does A battery does not produce charge. It separates + and - charge through chemical reactions and places them on the electrodes. This separation of charge produces a voltage between the terminals.

10. New NiMH rechargables – used in cell phones and laptops The new rechargable batteries use nickel as the positive electrode and a hydrogen- absorbing metal alloy as the negative electrode Similar to old Ni-Cd – but the hydrogen produced in cell is absorbed by the negative electrode To recharge - the hydrogen ion is removed and put back into the electrolyte by sending current in the opposite direction

11. Resources… Check you reading links in the CD www.energizer.comwww.energizer.com – has a learning center with a lot of resources