Figure 18 Voltage is increased for long-distance transmission, and then decreased near homes, schools, and businesses.
Interpreting Diagrams How many step-down transformers are shown in the figure?
dFollow the steps shown in Figure 18 from the point where electrical energy is generated. The power plant on the left generates electrical energy that is stepped up to hundreds of thousands of volts. Transformers, which are shown in the middle of the diagram, make it possible to bring electrical energy efficiently from the power plant to users. After traveling along the high-voltage transmission lines, the voltage is stepped down at a substation, to a few thousand volts. The electrical energy is then distributed to neighborhoods. Just before the electrical energy reaches people's homes, the voltage is stepped down to between 220 and 240 volts. Heavy duty appliances, like an electric stove, use 240-volt circuits. Most other appliances in the home use 120 volts.
Section 21.3 Assessment
Reviewing Concepts
How is voltage induced in a conductor?- Name two types of generators.
- How does a transformer work?
- Name six sources of electrical energy in the United States.
Critical Thinking
Relating Cause and Effect Explain how water can be used to create electrical energy.
Applying Concepts What is the connection between Faraday's law and the generation of electrical energy?
Comparing and Contrasting Describe how AC generators and DC generators are alike and how they are different.
Drawing Conclusions Why can't you use electrical energy directly from a high-voltage line?
Calculating An electronic device contains a transformer. Its primary coil has 200 turns, and its secondary coil has 20 turns. If the device is plugged into a 120-volt line, what is the output voltage of the device?
Writing in Science
Compare-Contrast Paragraph Write a paragraph comparing and contrasting what step-up and step-down transformers do. (Hint: Use the terms voltage, primary coil, secondary coil, input, and output.)
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