CHAPTER 21 Assessment

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Reviewing Content

Choose the letter that best answers the question or completes the statement.

1. Where is the field of a magnet strongest?

   1. near the north pole

   2. near the south pole

   3. near both poles

   4. near the middle

2. If you cut a magnet in half, you have

   1. no magnets.

   2. two half magnets.

   3. one magnet.

   4. two magnets.

3. A magnet's field lines always start near the magnet's

   1. middle.

   2. south pole.

   3. north pole.

   4. side.

4. A ferromagnetic material is

   1. always a magnet.

   2. a magnet if its domains are aligned.

   3. a magnet if its domains are not aligned.

   4. never a magnet.

5. An iron bar is placed in a solenoid to

   1. decrease the voltage.

   2. increase the voltage.

   3. increase the magnetic field strength.

   4. decrease the magnetic field strength.

6. Which of these cannot increase the strength of an electromagnet?

   1. making the loops smaller in the coil

   2. placing an iron bar in the coil

   3. winding more loops in the coil

   4. increasing the current in the coil

7. An electric generator converts

   1. electrical energy into mechanical energy.

   2. power into energy.

   3. mechanical energy into electrical energy.

   4. energy into power.

8. What effect does a magnetic field have on a charge moving perpendicular to the field?

   1. It has no effect.

   2. It pulls the charge forward.

   3. It pushes the charge backward.

   4. It pushes the charge perpendicularly to the field and the charge's velocity.

9. A galvanometer is a device used to measure

   1. current.

   2. resistance.

   3. voltage.

   4. magnetic field strength.

10. A transformer increases or decreases

    1. energy.

    2. resistance.

    3. voltage.

    4. direct current.

Understanding Concepts

11. What part of an atom is responsible for producing magnetic fields?

12. Why is iron easy to magnetize when used in an electromagnet?

13. How are magnetic domains in nonmagnetized materials different from the magnetic domains in magnetized materials?

14. Explain how you can determine the direction of a magnetic field produced by a wire if you know the direction of current through the wire.

15. The figure below shows a current-carrying wire between the poles of two magnets. In which direction is charge deflected by the magnetic field?

    

16. How can a change in the voltage of a transformer's primary coil create a change in the secondary coil's voltage, without the coils touching?

17. A transformer is connected to a 9-volt battery. A student tries to use this setup to double the voltage for an experiment. However, the output voltage is zero. Explain why.

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