How electricity is generated Reviews Exercises
5.10 How electricity is generated Reviews Exercises
1. Define the term “generator."
2. State the three major parts of a direct current generator.
3. With the aid of a sketch, explain how e.m.f. is induced in a direct current generator.
4. Explain how a simple direct current generator may be improved for greater e.m.f. induction.
5. Define the term ''piezoelectricity."
6. With the aid of sketches, explain how thermocouples may be used to produce a higher voltage.
7. Explain how solar cells produce electricity.
8. List three applications of solar cells in everyday life.
9. State two uses of geothermal energy.
How electricity is generated Key points
5.9 How electricity is generated Key points
1. A D.C. generator produces a unidirectional voltage and current.
2. The three major parts of a D.C. generator are stator, rotor and commutator.
3. The direction of the induced e.m.f. in straight conductor is determined by the Right-Hand Rule.
4. The direction of the induced e.m.f. in coil conductor or solenoid is determined by the Right-Hand Grip Rule.
5. Electrical energy may be generated by ways other than magnetism and chemical action.
6. A piece of electric crystal can generate electricity when subjected to a changing pressure across two of its sides (compressed or released).
7. A steady pressure applied to a piece of electric crystal will not generate electricity.
8. The most frequently used piezoelectric crystals are quartz, Rochelle salt and barium titanate.
9. Electricity is produced whenever there is a relative motion between two materials such as a glass rod and silk. This is called static electricity. We can simply say that electricity is produced by friction.
10. Radiant energy is another source of electricity:
a. a photovoltaic cell converts light energy into electricity,
b. all photovoltaic cells are composed of two layers of dissimilar semi-conductor materials.
11. When a light ray strikes the junction between the two layers of a photovoltaic cell, electrons are forced across it.
12. Modern solar cells are made of silicon and germanium semi-conductor material.
13. Geothermal energy is heat energy produced within the Earth.
14. Geothermal power is renewable and environmentally friendly.
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