Download Physics 2020 Spring 2008

Physics 2020 Fall 2016
Experiment Test, Electricity, Magnetism and Maxwell’s Equations
PUT YOUR ANSWERS ON A SCANTRON CARD!
Do the actual experimentation in groups but fill in your own conclusions
(i.e., you can talk to your classmates about the test and its results but you
fill out your own answers on your own scantron card).
Part 1: Procedure
Experimental materials for each group: copper pipe, plastic pipe, magnet cluster,
marbles. Keep these magnets away from credit cards and electronics.
Procedure:
1) have 1 person in the group hold the copper pipe vertically with the bottom end
a short distance above the floor.
2) Have a second person hold the magnet cluster, one of the flat faces down,
just above the open upper end of the pipe so that it will fall into the pipe when
released.
3) Have a third person hold the marble at the same height above the floor as the
magnet cluster but so that it will fall outside the pipe when released.
4) Release the magnet and marble at the same time and record your
observations. Repeat several times. Call this test A.
5) Do steps 1-5 again but this time with the marble falling through the pipe and
the magnet cluster falling well outside the pipe. Repeat several times. Record
your observations. Call this test B
6) Release the magnet and marble from the same height at the same time and
with both falling outside and well away from the pipe. Repeat several times.
Record the results. Call this test C.
7) Drop two marbles at the same time from the same height with one falling
through the pipe and one falling outside the pipe. Repeat until you get a
test without much friction between the marble in the pipe and the pipe.
Repeat several times. Record your results. Call this test D.
8) Each person should drop the magnets into the vertical pipe and then look
down the pipe as they fall (someone else should hold the pipe). Call this test
E.
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9) Test the copper pipe and the marbles with the magnets to see if either
respond to magnetic forces (i.e., stick to the magnet).
Call this test F. Record your results.
10) Repeat any of these steps as needed.
11) Be sure not to have any fun. This always invalidates the results.
Part 2: Observations (fill out questions on your scantron card)
Test A:
What hits ground first? (Note: in these tests if the object hit the floor nearly at the
same time select “same time”, i.e., ignore small differences)
1) Trial 1:
a) marble hit first
b) magnets hit first
c) same time
2) Trial 2:
a) marble hit first
b) magnets hit first
c) same time
3) Trial 3:
a) marble hit first
b) magnets hit first
c) same time
4) In this test were your results reasonably consistent?
a) yes
b) no
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Test B:
What hits ground first? (Note: in these tests if the object hit the floor nearly at the
same time select “same time”, i.e., ignore small differences)
5) Trial 1:
a) marble hit first
b) magnets hit first
c) same time
6) Trial 2:
a) marble hit first
b) magnets hit first
c) same time
7) Trial 3:
a) marble hit first
b) magnets hit first
c) same time
8) In this test were your results reasonably consistent?
a) yes
b) no
Test C:
What hits ground first? (Note: in these tests if the object hit the floor nearly at the
same time select “same time”, i.e., ignore small differences)
9) Trial 1:
a) marble hit first
b) magnets hit first
c) same time
10) Trial 2:
a) marble hit first
b) magnets hit first
c) same time
3
11) Trial 3:
a) marble hit first
b) magnets hit first
c) same time
12) In this test were your results reasonably consistent?
a) yes
b) no
Test D:
What hits ground first? (Note: in these tests if the object hit the floor nearly at the
same time select “same time”, i.e., ignore small differences)
13) Trial 1:
a) marble in pipe hit first
b) marble outside pipe hit first
c) same time
14) Trial 2:
a) marble in pipe hit first
b) marble outside pipe hit first
c) same time
15) Trial 3:
a) marble in pipe hit first
b) marble outside pipe hit first
c) same time
16) In this test were your results reasonably consistent?
a) yes
b) no
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Test E:
Carefully observe the magnets as they fall through the vertically held copper
pipe. Repeat until you are sure of your observations.
17) As the magnets fall through the pipe are large parts of the surfaces of the
magnets in contact for long periods of time or do the magnets seem to stay
mostly away from the pipe?
a) Large portions of the magnets are in contact with the pipe a lot of the time
b) the magnets tend to stay away from the sides of the pipe as much as
possible
18) What does the answer to the previous question seem to say about the role of
friction in the experiment?
a) friction is not enough of a factor to change the results
b) friction is enough of a factor to change the results
19) It is possible for friction to occur between the pipe and marble when a marble
falling through the pipe?
a) yes
b) no
20) Considering your answer to the previous question, is friction responsible for
your experimental results?
a) yes
b) no
21) As the magnets initially start falling from rest in the pipe are they accelerating
or not? Repeat the observation if necessary.
a) yes (ΣF ≠ 0)
b) no (ΣF = 0)
22) When the magnets have fallen more than halfway through the pipe do they
seem to be accelerating or not? Repeat the observation if necessary.
a) yes (ΣF ≠ 0)
b) no (ΣF = 0)
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Test F:
See if the magnets stick directly to the copper pipe (like they would to steel). Put
the magnet next to the outside of a copper pipe to test this. Then see if the
magnets stick directly to the glass marbles (like they would to steel).
23) Do the magnets exert any magnetic force on the pipe (do the magnets stick
to the metal of the pipe?
a. Yes
b. No
24) Do the magnets stick to the glass marbles?
a) yes
b) no
25) Can any direct attraction between the magnets and copper pipe explain
all the experimental results? (If there isn’t any such attraction the answer is
no)
a) yes
b) no
26) Can any direct attraction between the magnets and glass marbles explain all
the experimental results? (If there isn’t any such attraction the answer is no)
a) yes
b) no
Test G: Repeat test A with a plastic pipe instead of a copper one.
27) Trial 1:
a) marble hit first
b) magnets hit first
c) same time
28) Trial 2:
a) marble hit first
b) magnets hit first
c) same time
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29) Trial 3:
a) marble hit first
b) magnets hit first
c) same time
30) In this test were your results reasonably consistent?
a) yes
b) no
Test H: Repeat test B with a plastic pipe instead of a copper one
31) Trial 1:
a) marble hit first
b) magnets hit first
c) same time
32) Trial 2:
a) marble hit first
b) magnets hit first
c) same time
33) Trial 3:
a) marble hit first
b) magnets hit first
c) same time
34) In this test were your results reasonably consistent?
a) yes
b) no
Test I: Repeat test C with a plastic pipe instead of a copper one
35) Trial 1:
a) marble hit first
b) magnets hit first
c) same time
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36) Trial 2:
a) marble hit first
b) magnets hit first
c) same time
37) Trial 3:
a) marble hit first
b) magnets hit first
c) same time
38) In this test were your results reasonably consistent?
a) yes
b) no
Test J: Repeat Test D with a plastic pipe instead of a copper one
39) Trial 1:
a) marble in pipe hit first
b) marble outside pipe hit first
c) same time
40) Trial 2:
a) marble in pipe hit first
b) marble outside pipe hit first
c) same time
41) Trial 3:
a) marble in pipe hit first
b) marble outside pipe hit first
c) same time
42) In this test were your results reasonably consistent?
a) yes
b) no
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Part 3: Free body diagrams
In test C you dropped the magnets and marble both outside the pipe. If they
hit the floor at the same time or nearly at the same time, do you think air
resistance can be ignored. If so, do not include air resistance force vectors
in your free body diagrams.
Remember that if air resistance is not a significant factor, all objects falling
under the force of gravity alone (if weight is the only force) will fall at the
same rate and, if released at the same time from the same height, will hit a
level floor at the same time (barring small deviations from being released at
not exactly the same time, etc.)
43) Which of the following free body diagrams correctly describes the falling
marble in test A?
a) ΣF = mg
b) ΣF ≠ mg and ΣF ≠ 0
c) ΣF = 0
unknown force
unknown force
weight
weight
weight
44) Which of the following free body diagrams correctly describes the falling
magnets in test A (very shortly after the magnets start falling through the
copper pipe)?
a) ΣF = mg
b) ΣF ≠ mg and ΣF ≠ 0
c) ΣF = 0
unknown force
unknown force
weight
weight
weight
9
45) Which of the following free body diagrams correctly describes the falling
magnets in test A (after they have fallen through half the copper pipe)?
a) ΣF = mg
b) ΣF ≠ mg and ΣF ≠ 0
c) ΣF = 0
unknown force
unknown force
weight
weight
weight
46) Which of the following free body diagrams correctly describes the falling
marble in test B?
a) ΣF = mg
b) ΣF ≠ mg and ΣF ≠ 0
c) ΣF = 0
unknown force
unknown force
weight
weight
weight
10
47) Which of the following free body diagrams correctly describes the falling
magnets in test B?
a) ΣF = mg
b) ΣF ≠ mg and ΣF ≠ 0
c) ΣF = 0
unknown force
unknown force
weight
weight
weight
48) Which of the following free body diagrams correctly describes the falling
marble in test C?
a) ΣF = mg
b) ΣF ≠ mg and ΣF ≠ 0
c) ΣF = 0
unknown force
unknown force
weight
weight
weight
11
49) Which of the following free body diagrams correctly describes the falling
magnets in test C?
a) ΣF = mg
b) ΣF ≠ mg and ΣF ≠ 0
c) ΣF = 0
unknown force
unknown force
weight
weight
weight
50) Which of the following free body diagrams correctly describes the falling
marble inside the pipe in test D?
a) ΣF = mg
b) ΣF ≠ mg and ΣF ≠ 0
c) ΣF = 0
unknown force
unknown force
weight
weight
weight
12
51) Which of the following free body diagrams correctly describes the falling
marble outside the pipe in test B?
a) ΣF = mg
b) ΣF ≠ mg and ΣF ≠ 0
c) ΣF = 0
unknown force
unknown force
weight
weight
weight
52) Which of the following free body diagrams correctly describes the falling
marble in test G?
a) ΣF = mg
b) ΣF ≠ mg and ΣF ≠ 0
c) ΣF = 0
unknown force
unknown force
weight
weight
weight
13
53) Which of the following free body diagrams correctly describes the falling
magnets in test G?
a) ΣF = mg
b) ΣF ≠ mg and ΣF ≠ 0
c) ΣF = 0
unknown force
unknown force
weight
weight
weight
54) Which of the following free body diagrams correctly describes the falling
marble in test H?
a) ΣF = mg
b) ΣF ≠ mg and ΣF ≠ 0
c) ΣF = 0
unknown force
unknown force
weight
weight
weight
14
55) Which of the following free body diagrams correctly describes the falling
magnets in test J?
a) ΣF = mg
b) ΣF ≠ mg and ΣF ≠ 0
c) ΣF = 0
unknown force
unknown force
weight
weight
weight
56) Which of the following free body diagrams correctly describes the falling
marble in test I?
a) ΣF = mg
b) ΣF ≠ mg and ΣF ≠ 0
c) ΣF = 0
unknown force
unknown force
weight
weight
weight
15
57) Which of the following free body diagrams correctly describes the falling
magnets in test I?
a) ΣF = mg
b) ΣF ≠ mg and ΣF ≠ 0
c) ΣF = 0
unknown force
unknown force
weight
weight
weight
58) Which of the following free body diagrams correctly describes the falling
marble inside the pipe in test J?
a) ΣF = mg
b) ΣF ≠ mg and ΣF ≠ 0
c) ΣF = 0
unknown force
unknown force
weight
weight
weight
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Part 4: Review Questions about Maxwell’s Equations
59) Which of the following says that isolated positive and negative charges can
exist in our universe?
a) ∮BdL = 0I + 00(E/t)
b) ∮B•da = 0
c) ∮EdL = -B/t
d) ∮E•da = qencl/ε0
60) Which of the following says that isolated magnetic poles must occur in pairs
(in other words, isolated magnetic poles cannot exist)?
a) ∮BdL = 0I + 00(E/t)
b) ∮B•da = 0
c) ∮EdL = -B/t
d) ∮E•da = qencl/ε0
61) What does ∫ mean?
a) it means you are multiplying
b) it means vector multiplication
c) it means vector addition
d) it means you are adding something
62) What does ∮ mean?
a) it means vector addition
b) it means you are adding something around a surface without holes
c) it means you are adding something around an unbroken loop
d) it means the zero integral
e) b and c
63) Which of the following is the only Maxwell’s equation containing a variable for
electric current?
a) ∮BdL = 0I + 00(E/t)
b) ∮B•da = 0
c) ∮EdL = -B/t
d) ∮E•da = qencl/ε0
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64) Which of the following is the only Maxwell’s equation that says that an
electric current can cause magnetic effects?
a) ∮BdL = 0I + 00(E/t)
b) ∮B•da = 0
c) ∮EdL = -B/t
d) ∮E•da = qencl/ε0
65) What does B/t mean?
a) 2 times the magnetic flux divided by 2 times the time
b) the change of electric flux with time
c) the magnetic flux
d) the change in the magnetic flux with time
e) the change in flux with time
66) Which of the following is the Maxwell’s Equation that says changing the
magnetic flux has electrical effects?
a) ∮BdL = 0I + 00(E/t)
b) ∮B•da = 0
c) ∮EdL = -B/t
d) ∮E•da = qencl/ε0
67) Which of Maxwell’s Equations say that electricity and magnetism are related?
a) ∮BdL = 0I + 00(E/t)
b) ∮B•da = 0
c) ∮EdL = -B/t
d) ∮E•da = qencl/ε0
e) a and c
Part 5: Analysis of Experimental Results. Clearly indicate the best choice of
answer to each question.
68) Is the copper pipe made out of an electrical conductor?
a) Yes
b) No
c) I dunno
69) Is the plastic pipe made out of an electrical conductor?
a) Yes
b) No
c) Moan
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70) When the magnet is falling through either pipe, the magnetic field is
static and unchanging relative to what?
a) The magnet itself
b) The pipes
c) Neither the magnet itself or the pipes
71) Now suppose we, in our minds, divide the either pipe into a series of
horizontal sections. These sections will take the form of loops in a horizontal
plane. What change in the magnitude of the magnetic field vector will occur
through the area bounded by a loop as the magnets approach:
a)
b)
c)
d)
the magnetic field vector increases in strength
the magnetic field vector decreases in strength
the magnetic field vector does not change in strength
there is no magnetic field vector there at all
72) As the magnets fall through the either pipe and approach any of the loops
what will happen to the magnitude of the magnetic flux through the area
bounded by the loop?
a)
b)
c)
d)
the magnetic flux increases
the magnetic flux decreases
the magnetic flux does not change
there is no magnetic flux there at all
73) Again suppose we, in our minds, divide the pipes into a series of
horizontal sections. These sections will take the form of loops of pipe in a
horizontal plane. As the magnets fall through the pipe, what change in the
magnitude of the magnetic field vector will occur through the area bounded by
any loop as the magnets fall away from the loop:
a)
b)
c)
d)
the magnetic field vector increases in strength
the magnetic field vector decreases in strength
the magnetic field vector does not change in strength
there is no magnetic field vector there at all
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74) As the magnets fall through either pipe and fall away from any of the
loops what will happen to the magnitude of the magnetic flux through the area
bounded by any loop?
a)
b)
c)
d)
the magnetic flux increases
the magnetic flux decreases
the magnetic flux does not change
there is no magnetic flux there at all
75) When the magnets fall outside either pipe how does the amount of
magnetic flux they create through the area bounded by any of the pipe loops
compare to the magnetic flux through the area they generate while falling
inside the pipe? Consider the shape of the magnetic field and its distance
from the area bounded by any loop (magnetic fields weaken with distance
from the magnet).
a)
b)
c)
d)
This magnetic flux is greater when the magnets fall inside either pipe
This magnetic flux is greater when the magnets fall outside either pipe
The magnetic flux through the area is the same in each case
There is no magnetic flux through the area bounded by a loop at all
76) When a marble falls inside or outside either pipe, what change occurs in
magnetic flux through the area bounded by any loop in the pipe?
a) The same changes in flux that occur when the magnets fall inside
either pipe
b) No change in magnetic flux occurs at all
c) The opposite of the changes that occur when the magnets fall inside
either pipe
d) A steady magnetic flux
77) If a loop is made of a material that conducts electricity, what happens
when the magnetic flux through the loop (and hence through the area
bounded by the loop) changes?
a)
b)
c)
d)
Nothing
An electric current occurs in the loop (magnetic induction)
Static electric charges concentrate in the loop
Another magnetic field is generated directly
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78) If a loop is made of a material that doesn’t conduct electricity, what
happens when the magnetic flux through the loop (and hence through the
area bounded by the loop) changes?
a) Nothing
b) An electric current occurs in the loop (magnetic induction)
c) Static electric charges concentrate in the loop
d) Another magnetic field is generated directly
79) Will the change in magnetic flux through sections of the plastic pipe do
anything?
a) Yes
b) No
80) Which of the following situations should create the strongest induced
current in any loop section of the copper pipe?
a)
b)
c)
d)
Magnets falling inside the pipe
Magnets falling outside the pipe
Marble falling inside the pipe
Marble falling outside the pipe
81) Which of the following situations should create the strongest induced
current in any loop section of the plastic pipe?
a)
b)
c)
d)
e)
Magnets falling inside the pipe
Magnets falling outside the pipe
Marble falling inside the pipe
Marble falling outside the pipe
There will be no electric current induced in the plastic pipe at all
82) When a current is induced in any of the loops of the copper pipe, what
does it cause?
a)
b)
c)
d)
More electric current
Nothing
A second magnetic field
Green eggs and ham
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83) Which of Maxwell’s equations describes the effect in the previous
question?
a)
b)
c)
d)
Ampere’s Law
Faraday’s Law
Gauss’s Law of Electricity
Gauss’s Law of Magnetism
84) Which of the following situations should create the strongest secondary
magnetic field?
a)
b)
c)
d)
e)
Magnets falling inside the copper pipe
Magnets falling outside the copper pipe
Magnets falling inside the plastic pipe
Marbles falling inside the copper pipe
Marbles falling inside the plastic pipe
85) The secondary magnetic field (created by the induced current) always
has what relation to the change in magnetic flux caused by the falling
magnets in the copper pipe?
a)
b)
c)
d)
The secondary magnetic field will oppose the change in flux
The secondary magnetic field will reinforce the change in flux
There will be no relation whatever
Orlon from Omicron V needs a fudgecake
86) Magnetic fields can exert forces on magnets. Considering Lenz’s Law,
what effect will the secondary magnetic field have on the falling magnets
in the copper pipe?
a)
b)
c)
d)
It will assist the motion of the falling magnets
There will be no such effect
It will exert a force opposing the movement of the magnets
Orlon from Omicron V still needs a fudgecake
87) What effect will the phenomenon described in the previous question have
in this experiment?
a)
b)
c)
d)
e)
It will slow the fall of the magnets through the copper pipe
It will quicken the fall of the magnets through the copper pipe
It will slow the fall of the marble through the copper pipe
It will slow the fall of the marble outside the copper pipe
It will quicken the fall of the marble through the copper pipe
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88) When an electric current forms in a loop, the magnetic field generated
will be concentrated inside the loop but will not be as strong outside the
loop. With this in mind, and considering any other factors, do you think the
effect described in the previous several questions will be greater for:
a)
b)
c)
d)
e)
The magnets falling inside the copper pipe
The magnets falling outside the copper pipe
The marble falling inside the copper pipe
The marble falling outside the copper pipe
The magnets falling inside the plastic pipe
89) If we cancel Lenz’s Law (the negative sign in Faraday’s Law), the
magnets falling through the copper pipe
a) Would fall faster than in a universe with Lenz’s Law
b) Would fall slower than in a universe with Lenz’s Law
c) Will fall at the same rate as in a universe with Lenz’s Law
90) If we cancel Lenz’s Law (the negative sign in Faraday’s Law), the
magnets falling through the plastic pipe
a) Would fall faster than in a universe with Lenz’s Law
b) Would fall slower than in a universe with Lenz’s Law
c) Will fall at the same rate as in a universe with Lenz’s Law
91) The force exerted by the secondary magnetic field on any of the
falling objects will be strongest when:
a)
b)
c)
d)
e)
The marble is falling inside the copper pipe
The marble is falling outside the copper pipe
The magnets are falling outside the copper pipe
The magnets are falling inside the copper pipe
The magnets are falling inside the plastic pipe
92) The greatest departure from a normal fall speed occurs when:
a)
b)
c)
d)
e)
The marble is falling inside the copper pipe
The marble is falling outside the copper pipe
The magnets are falling outside the copper pipe
The magnets are falling inside the copper pipe
The magnets are falling inside the plastic pipe
23
93) All the marbles and magnets experience the force of weight. Ignoring air
resistance, which of the following is experiencing an additional force?
a) the marble outside the copper pipe
b) the marble inside the copper pipe
c) the magnets inside the copper pipe
d) the magnets outside the copper pipe
e) the magnets inside the plastic pipe
94) What is it that is directly exerting this force?
a) a secondary magnetic field manifesting Lenz’s Law
b) an electric field
c) the magnetic field of the magnets
d) the magnetic field of the pipe
95) What is it that causes the secondary magnetic field?
a) a magnet
b) an electric current
c) an electric field
96) For the correct answer to the previous question, which of Maxwell’s
Equations is involved?
a) Gauss’s Law of Magnetism
b) Gauss’s Law of Electricity
c) Faraday’s Law
d) Ampere’s Law
97) For the correct answer to question the previous two questions, which of
the following is involved?
a) ∮BdL = 0I + 00(E/t)
b) ∮B•da = 0
c) ∮EdL = -B/t
d) ∮E•da = qencl/ε0
98) What causes the cause of the upward force?
a) the change in magnetic flux in the copper pipe created by the falling
magnet
b) the electric current in the copper pipe
c) Lenz’s Law
d) the change in magnetic flux caused by the electric current
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99) Which of the following explains the cause of the cause of the upward
force?
a) ∮BdL = 0I + 00(E/t)
b) ∮B•da = 0
c) ∮EdL = -B/t
d) ∮E•da = qencl/ε0
100) Which of the following sequence of events explains best what you saw in
this experiment when the magnets fell through the copper pipe?
a) the magnet is directly attracted to the copper pipe
b) the changing magnetic field caused by the falling magnet creates an
electric current that in turn creates a secondary magnetic field that
then opposes what created it (the motion of the falling magnet)
c) the changing magnetic field created by the falling magnet creates a
secondary magnetic field that opposes the falling motion of the magnet
d) the changing magnetic field caused by the falling magnet creates an
electric current that in turn creates a secondary magnetic field that
then assists what created it (the motion of the falling magnet)
e) the electric field of the falling magnet creates a secondary magnetic
field that opposes what created it (the fall of the magnet)
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