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Application and Critical Thinking

Reviewing and Extending

SUMMING UP

1) A lodestone is a kind of rock that has special properties called magnetic properties. Objects hav­ing these special properties are called magnets.

A magnet that is free to turn in any direction will always line up so that one end, or pole, is pointed in a northerly direction.

The pole of a magnet that points toward the north is called a north-seeking, or north, pole. The

Other pole is a south-seeking, or south, pole.

One model for magnets suggests that a magnet is made up of many small magnets.

Oersted discovered that electricity produces a magnetic field.

A magnet made by using electricity in loops of wire is called an electromagnet.

Faraday discovered how to make electricity from a magnetic field.

Transformers are used for changing the voltage of alternating-current electricity.

CHECKING UP

Vocabulary

Write the numerals 1-5 on your paper. Each numbered phrase describes a term from the following list. On your paper, write the term next to the numeral of the phrase that describes it.

pole model lodestone

magnetic transformer North Star

 

1) used to explain certain observations

2) star called the leading star

3) rock with part that always faces the same direction

4) used to change the voltage of alternating-current electricity

5) end of a magnet

 

Knowledge and Understanding

Write the numerals 6-9 on your paper. Beside each numeral, write the word or words that best com­plete the sentence having that numeral.

6) A transformer that puts. out a greater voltage than is put into it is called a ……… transformer.

7) The end of a magnet that always points toward the north is called the …………… .

8) The process of ……. is what makes alternating-current transform­ers possible.

9)The person who discovered how to use magnets to produce elec­tricity was ……… .

 

Concepts

Beside each of the numerals 10-13 on your paper, write the word or words that best complete the sentence having that numeral.

10) The reason sailors used lodestones was that lodestones (attracted iron filings, pointed north, stopped sudden storms).

11) The amount of attracting and repelling between magnets is great­est at the (centers, coils, poles) of the magnets.

12) An electromagnet uses (electricity to make magnetism, magnetism to make electricity, electricity to make voltage).

13) Iron filings may be used with a magnet to show that there is a (model, magnetic field, loop of wire) all around a magnet.

 

Application and Critical Thinking

Answer the following ques­tions as briefly as you can without leaving out any important ideas.

14) Look at the transformer pictured on the right. Is it a step-up or a

step-down transformer? What effect does it have on the voltage in

a circuit?

15) In what ways are electromagnets like other magnets? In what ways

are they different?

 





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