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16. The north pole of a suspended or floating bar magnet currently 26. Electromagnetic induction occurs when a coil of wire cuts across
points directly toward Earth’s magnetic field lines. Which one of the following increases the
a. north magnetic pole. voltage produced?
b. south magnetic pole. a. Fewer wire loops in the coil
c. north geographic pole. b. Increased strength of the magnetic field
d. south geographic pole. c. Slower speed of the moving coil of wire
17. A current-carrying wire always has d. Decreased strength of the magnetic field
a. a magnetic field with closed concentric field lines around the 27. Electric power companies step up the voltage of generated power
length of the wire. for transmission across the country because higher voltage
b. a magnetic field with field lines parallel to the length of the wire. a. means more power is transmitted.
c. an electric field but no magnetic field around the wire. b. reduces the current, which increases the resistance.
d. nothing in the space around the wire. c. means less power is transmitted.
18. Magnetism is produced by d. reduces the current, which lowers the energy lost
a. an excess of north monopoles. to resistance.
b. an excess of south monopoles. 28. A solar cell
c. moving charges. a. produces electricity directly.
d. separation of positive and negative charges. b. requires chemical reactions.
19. Earth’s magnetic field c. has a very short lifetime.
a. has undergone many reversals in polarity. d. uses small moving parts.
b. has always been as it is now. 29. Which of the following is most likely to acquire an electrostatic
c. is created beneath Earth’s north geographic pole. charge?
d. is created beneath Earth’s south geographic pole. a. Electrical conductor
20. The strength of a magnetic field around a current-carrying wire b. Electrical nonconductor
varies directly with the c. Both are equally likely
a. amperage of the current. d. None of the above is correct
b. voltage of the current. 30. Which of the following units are measures of rates?
c. resistance of the wire. a. Amp and volt
d. temperature of the wire. b. Coulomb and joule
21. Reverse the direction of a current in a wire, and the magnetic c. Volt and watt
field around the wire will d. Amp and watt
a. have an inverse magnitude of strength. 31. You are using which description of a current if you consider a
b. have a reversed north pole direction. current to be positive charges that flow from the positive to the
c. become a conventional current. negative terminal of a battery?
d. remain unchanged. a. Electron current
22. The operation of which of the following depends on the b. Conventional current
interaction between two magnetic fields? c. Proton current
a. Car stereo speakers d. Alternating current
b. Telephone 32. In an electric current, the electrons are moving
c. Relay circuit a. at a very slow rate.
d. All of the above b. at the speed of light.
23. An electric meter measures the c. faster than the speed of light.
a. actual number of charges moving through a conductor. d. at a speed described as supersonic.
b. current in packets of coulombs. 33. In which of the following currents is there no electron
c. strength of a magnetic field. movement from one end of a conducting wire to the
d. difference in potential between two points in a conductor. other end?
24. When a loop of wire cuts across magnetic field lines or when a. Electron current
magnetic field lines move across a loop of wire, b. Direct current
a. electrons are pushed toward one end of the loop. c. Alternating current
b. an electrostatic charge is formed. d. None of the above
c. the wire becomes a permanent magnet. 34. If you multiply amps by volts, the answer will be in units of
d. a magnetic domain is created. a. resistance.
25. A step-up transformer steps up the b. work.
a. voltage. c. current.
b. current. d. power.
c. power. 35. A permanent magnet has magnetic properties because
d. energy. a. the magnetic fields of its electrons are balanced.
b. of an accumulation of monopoles in the ends.
c. the magnetic domains are aligned.
d. all of the above.

6-35 CHAPTER 6 Electricity 173