PHY 102 - Chapter 11 Test Exam Questions and Answers (100% Pass)
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PHY 102 - Chapter 11
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PHY 102 - Chapter 11
PHY 102 - Chapter 11 Test Exam Questions and Answers (100% Pass)
Is it possible to have two permanent magnets that always attract one another, regardless of their relative orientations? Explain. - Answers No, because the magneostatic forces between magnetic dipoles depend on their relative orienta...
PHY 102 - Chapter 11 Test Exam Questions and Answers (100% Pass)
Is it possible to have two permanent magnets that always attract one another, regardless of their
relative orientations? Explain. - Answers No, because the magneostatic forces between magnetic dipoles
depend on their relative orientations.
Magnetic monopoles have never been found to exist in our universe; therefore, two permanent
magnets either attract or repel depending on their relative orientations.
If you bring two magnetic compasses nearby, they will soon begin attracting one another. Why don't
they repel - Answers The two compass needles rotate until they have minimized their total magneostatic
potential energies and thus the opposite poles will point toward one another.
The compass needles will want to move toward equilibrium in which the total magneostatice potential
energies are minimal which occurs with the opposite poles closest to one another and thus, the needles
are attracted.
If you bring a button magnet near an iron pipe, they will soon begin attracting one another. Why don't
they repel? - Answers The button magnet's magnetic field polarizes the iron pipe and the pipe develops
an opposite pole near the approaching pole of the button magnet and thus attracts the magnet.
With the button magnet nearby, opposite poles in the iron shift closer to the magnet and attract the
magnet.
If you hold a permanent magnet the wrong way in an extremely strong magnetic field, its magnetization
will be permanently reversed. What happens to the magnetic domains inside the permanent magnet
during this process? - Answers The magnetic domains of the permanent magnet that are aligned with
the applied magnetic field grow while the domains opposite to the applied magnetic field shrink.
Individual magnetic domains can grow or shrink depending on which way they are oriented
magnetically.
Hammering or heating a permanent magnet can demagnetize it. What happens to the magnetic
domains inside it during these processes? - Answers The magnetic domains will lose their uniform
orientations and become more randomly oriented.
, Hammering or heating a permanent magnet makes it easier for the magnetic dipoles to shift their
relative orientations.
Your friends are installing a loft in their room and are using thin speaker wires to provide power to an
extra outlet. If they draw only a small amount of current from the outlet, the voltage drop in each of the
wires will remain small. Why? - Answers The voltage drop is directly proportional to the current.
Ohm's law states that the potential difference (voltage drop) is directly proportional to the current.
A particular lightbulb is designed to consume 40 W when operating on a car's 12-V DC electric power. If
you supply that bulb with 12-V AC power from a transformer, how much power will it consume? -
Answers 40 W.
The lightbulb will consume the same amount of power it was designed to consume. The average power
of an AC source is the same power provided as a DC source.
Your toaster consumes 800 W when operating on 120-V AC electric power. If your rugby team is
camping and all of you string together flashlight batteries to supply that toaster with 120-V DC electric
power, how much power will it consume? - Answers 800 W.
The toaster will consume the same amount of power it was designed to consume. The average power of
an AC source is the same power provided as a DC source.
To read the magnetic strip on an ID or credit card, you must swipe it quickly past a tiny coil of wire. Why
must the card be moving for the coil system to read it? - Answers A moving magnet will induce a current
in the coil so that the magnetic strip can be read.
Only moving magnets or a changing magnetic field will produce the electric field necessary to push
currents through the coil.
If the primary coil of a transformer has 200 turns and is supplied with 120-V AC power, how many turns
must the secondary coil have to provide 12-V AC power? - Answers 20 turns.
secondary voltage = primary voltage · (secondary turns / primary turns)
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