1. Dry cell 1-carbon cell

2. carbon cell 1-The electrolyte is a moist paste inside the cell. 2-The outside case of the battery is usually made of zinc case. It is the negative electrode. 3-The positive electrode is some ­ times made of carbon rode. It is inside the dry cell.

3. Another type of dry cell is 2-The nickel- ­ cadmium cell. 1-The positive electrode is made of nickel oxide. 2-The negative electrode is made of cadmium.

4. An electric generator (dynamo) : is a device that converts mechanical energy into electrical energy.

6. An electric generator can be built rather like a motor; an electric generator is made up of : 1-an insulated loop of wire. 2- a U-shaped magnet. 3-The loop of wire is attached to two slip-rings 4- carbon brushes.

10. What is the different between D.C. generator and A.C. generator ? AC generator has two slip-rings But DC generator has commentator.

13. The voltage (and the current) of a generator can be increased by: 1- Using a coil with more turns. 2- Using a stronger magnet. 3-Rotating the coil faster. 4-Using a coil with a larger area.

14. Why we use AC instead of DC in household electricity ? Because AC produces less heat.

15. The heating effect of a current can also be used to protect circuits from dangerous over-heating.

16. Circuit breaker: is an automatic switch that opens a circuit when the current is overloaded.

18. Fuse: is a short piece (a wire) of metal that will melt and breaks a circuit if too large a current passes through it.

20. The electric power: is the rate of transferring Energy.