1. Cells & Batteries

2. Cells & Batteries
A cell a device that converts chemical energy into electrical energy.
A battery is two or more electric cells, joined and used as a source of electric current.

3. Where does electricity come from?
Generators are the most common source of electricity
Hydroelectric generators
Coal fired generators
Oil fired generators

4. Hydroelectric generators

5. Voltage of Cells & Batteries
A volt is the unit used to measure voltage
The SI unit is V
The more voltage a cell has, the more energy is supplied to the electrons that leave the cell to produce an electric current

6. Voltage of Cells & Batteries
Voltage in the Battery = Sum of Voltage in the
Cells in the Battery
Example:
A flashlight uses 2 D-size batteries with 1.5 V cells.
Voltage in the flashlight battery = 1.5 V V
= 3 V

7. Measuring Voltage A voltmeter is used to measure voltage
It looks like a galvanometer, but measures voltage not current.

8. Measuring Voltage To connect a voltmeter to a cell,
Connect the positive (+) to positive (+)
and
Connect the negative (-) to negative (-)

9. Types of Cells & Batteries
All cells have two features in common:
1) Presence of two different metals in the cell
The metals are called the electrodes
2) Separation of the metals by a solution
The solution is called the electrolyte

10. Types of Cells & Batteries
All batteries contain:
Electrodes  the metals
An Electrolyte  the solution

11. Diagram of Zinc-Carbon Cell

12. Resistance
A resistor is a device made of material that offers resistance to the flow of charges

13. Resistance
For a current to exist in a wire, the electrons must move past the atoms within the wire.
The greater the resistance of a material, the greater the amount of energy the electrons give up as they pass through it.

14. Resistance