Download Document

Name ______________________________ Class ___________________ Date __________________
GOLDSBERRY
Chapter 18 Section 3 Reading
Section: Electricity from Magnetism
ELECTRIC CURRENT FROM A CHANGING MAGNETIC FIELD
1. What problem did both Joseph Henry and Michael Faraday work to solve?
_______________________________________________________________
_______________________________________________________________
2. The process of creating a current in a circuit by changing a magnetic field is
called ______________________.
3. Describe what happened to the electric current in Michael Faraday’s
experiment when the battery was fully connected.
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
4. Describe two ways to induce a larger electric current when you move a magnet
in a coil of wires.
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.
Holt Science and Technology
8
Electromagnetism
Name ______________________________ Class ___________________ Date __________________
Directed Reading A continued
ELECTRIC GENERATORS
_____ 5. What device converts mechanical energy into electrical energy?
a. electric motor
c. electromagnetic motor
b. electric generator
d. magnetic motor
_____ 6. When electric current changes direction it is called a(n)
a. generated current.
c. alternating current.
b. electromagnetic current.
d. rotating current.
7. Name the four parts of a simple generator, and describe what they do.
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
8. Other than the size, what is one difference between power plants and electric
generators?
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
9. Name two sources of energy that generators convert into electrical energy.
_______________________________________________________________
_______________________________________________________________
Put the following steps for generating electrical energy in order from 1 to 4. Write
the appropriate numbers in the space provided.
_____ 10. Steam turns a turbine.
_____ 11. Energy boils water into steam.
_____ 12. Electric current is induced and electrical energy is generated.
_____ 13. A turbine turns the magnet of a generator.
Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.
Holt Science and Technology
9
Electromagnetism
Name ______________________________ Class ___________________ Date __________________
Directed Reading A continued
TRANSFORMERS
_____ 14. A device that increases or decreases the voltage of alternating current is
called a(n)
a. voltmeter.
c. transformer.
b. generator.
d. electromagnet.
15. Explain why a transformer uses different numbers of loops in its primary and
secondary coils.
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
16. Describe what a step-up transformer does.
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
17. Describe what a step-down transformer does.
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.
Holt Science and Technology
10
Electromagnetism