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21.3 Electrical Energy Generation and Transmission. Assessment Questions 1-8. Generating electric current. Electric current creates a magnetic field
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21.3 Electrical Energy Generation and Transmission Assessment Questions 1-8
Generating electric current • Electric current creates a magnetic field • LT #2: Demonstrate and explain that an electric current flowing in a wire will create a magnetic field around that wire (electromagnetic effect) [Motors] • A magnetic field can be used to produce an electric current = electromagnetic Induction = generator effect • LT #3: Demonstrate and explain that moving a magnet near a wire will cause an electric current to flow in the wire (the generator effect) [Generators]
1. How is voltage induced in a conductor? • Conductors are materials through which charge can flow easily (metal wires) • Voltage is induced in a conductor by a changing magnetic field. • So if you move a magnet near a conductor electric current is generated
2. Name two types of generators. • AC = alternating current; charges flow in one direction then reverse direction & converts mechanical energy into electrical energy • LT #1: Demonstrate and explain that an electric current flowing in a wire will create a magnetic field around that wire (electromagnetic effect) • DC = direct current; the current that leaves the generator flows only in one direction • Most power plants use AC because sending power over long distances & DC causes too much heat in wires
3. How does a transformer work? • A transformer increases or decreases voltage and current of 2 linked AC circuits • It changes voltage and current by generating a changing magnetic field in one coil. • This field then induces a current in a nearby coil with a different # of turns. • We need transformers to step up power to send it over long distances & step down power to make it safe to use in homes
4. Name the 6 sources of electrical energy in the United States. • Coal • Nuclear power • Water = hydroelectric • Wind • Natural gas • Petroleum
5. How can water be used to create electrical energy? • Water can turn a turbine (PE KE mechanical) • The turbine turns an axle of a generator & produces electricity (mechanical electrical) • LT #1: Describe a situation where energy is transformed from one form to another.
6. What is the connection between Faraday’s law & the generation of electrical energy? • Faraday’s law = a voltage is induced in a conductor by a changing magnetic field • The relative motion of a magnet & a coil of wire will cause charges to flow in the wire generating electric current and electrical energy
7. How are AC & DC alike? How are they different? • Both produce electric current by rotation of wire coil in a magnetic field • In a DC generator current only flows in one direction
8. Why can’t we use electrical energy directly from a high voltage line? • We’d fry! • High voltages are dangerous & household devices are designed to use much lower voltages