Electromagnetism Electromagnetism

Electrical Energy for Your Home The electric current that
provides your home with electrical energy is usually transformed
three times before it reaches your home. Generators at the
power plants produce electric current with high voltage. To
decrease the loss of power that occurs during transmission over
long distance, the voltage is increased thousands of times with
a step-up transformer. Of course, the voltage must be decreased
before it is distributed to households. Two different step-down
transformers are used before the electric current reaches consumers.
Figure 27 shows how electric current is transformed on
its way to your home.
Figure 27 Electric current is transformed
three times before reaching your home.
REVIEW
Home-supply (120 V) step-down transformer
Power plant, high voltage Step-up transformer Transmission lines, very high voltage
1. How does a generator produce an electric current?
2. Explain why rotating either the coil or the magnet induces
an electric current in a generator.
3. Inferring Conclusions One reason why electric power
plants do not distribute electrical energy as direct current
is that direct current cannot be transformed. Explain
why not.
Copyright © by Holt, Rinehart and Winston. All rights reserved.
3
Local power lines,
lower voltage
1
2
NSTA
Distribution station
step-down transformer
TOPIC: Electromagnetic Induction
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Electromagnetism 473