ACT reading practice test 30

DIRECTIONS: Each passage is followed by several questions. After reading a passage, choose the best answer to each question and fill in the corresponding oval on your answer document. You may refer to the passages as often as necessary.


Natural Science

This passage is adapted from "The Truth Behind Lightsaber Technology" by Matt Gluesenkamp (©2010 General Electric).

There are a lot of myths and legends about lasers that
Hollywood has generated or perpetuated over the years,
but perhaps the most well-known instance of "lasers" in
cinema are the lightsabers from the Star Wars
05saga. I put quotes around "lasers" because the way
lightsabers behave in these movies is quite a bit
different from the way lasers behave in real life.
In the Star Wars universe, lightsabers are typically
custom-built by Jedi and Sith warriors, and all have
10several common elements. Each has a power source, a
lightsaber crystal, one or more focusing crystals, and a
stabilizing emitter system. The power source is typically
a diatium power cell, often with a capacity of several
megawatt-hours. The lightsaber crystal converts the
15power cell's energy into a plasma that is then
passed through and directed by the focusing crystals.
Finally, the emitter system stabilizes the plasma
into a blade shape using a mix of power modulation
and magnetic field containment.
20Did that make sense to anyone No Good, then I'm not
alone. Science fiction is typically a blend of materials
or physical laws that exist and some that don't. Although
real-life battery technology is coming along great, we
are a long way off from creating handheld batteries
25with capacities like the ones found in the lightsaber's
diatium power cell. Perhaps the key lies in discovering
this fictional "diatium" material And although crystals
do have many useful optical and piezoelectric properties,
I don't know of one that could magically
30create plasma from electricity. (However, I read
that the crystals must be "attuned to the Force" by a Jedi
or Sith in a meditation ritual that can take days, so maybe
we should start there.)
Where the explanations of lightsaber technology get
35really convoluted is when they start talking about
how the blade is shaped and contained. Magnetic fields
are currently used to contain plasmas, but they are
generated by machinery that must also surround it-generating
such a magnetic envelope from a single, unidirectional
40source would likely require some new laws of physics.
There are no crystals that can "direct" a plasma.
In fact, a plasma being "directed" by a crystal lens
doesn't even make any physical sense. A plasma is really
just an ionized gas-a gas in which the electrons have
45been stripped from their atomic nuclei. We see plasmas
all the time. They make up and are emitted from every star,
like our solar wind and solar flares. The interaction of the
solar wind with Earth's magnetic field produces the aurora
borealis
, or northern lights-another form of plasma.
50Plasmas are also the stuff of every spark and
lightning bolt.
Plasmas can be created by bringing gases up to a high
energy level. The higher the energy, the more atoms will
be stripped of their electrons, and the better quality
55plasma we will have. It's completely possible that
one could create a plasma by producing a large enough
voltage difference-as with lightning-or a powerful
enough laser focus. However, enormous amounts of energy
are required with either of these approaches, and
60it would be extremely difficult to control the plasma's
shape. An electrical arc can have wild shifts in direction,
and it can hardly be controlled without being surrounded
by magnets. A laser will go in a straight line… but,
of course, it doesn't stop. A laser-based lightsaber would
65require a block or a couple of mirrors floating in
midair, moving in sync with the hilt, which is largely
impossible. On top of that, they would certainly melt in the
presence of such a plasma anyway. Furthermore, all of this
says nothing about what the actual quality of the plasma
70would be and how reliably or quickly it would cut
through objects.
So it seems quite impossible to create a lightsaber, as
seen in the Star Wars films, using existing technologies,
materials, and physical laws. But given the enthusiasm of
75Star Wars superfans out there, I wouldn't be surprised
if people are trying.

1. The author of this passage would most likely agree with which of the following statements?

A. The authors who invented science-fiction never intended for it to depict things like lightsabers.
B. Science-fiction films can give people inaccurate ideas about the world that really surrounds them.
C. One should "never say never," because anything might be possible someday.
D. The content of science-fiction films should be more carefully regulated by the government.

2. The main point of the fifth paragraph (lines 42-51) is that:

F. real-life crystals are not nearly powerful enough to direct plasma at high temperatures.
G. studying lightning would be the logical first step in the construction of a lightsaber.
H. the commonness of plasmas in the real world is a good sign for lightsaber technology.
J. the idea of plasma having a predetermined shape is inherently absurd.

3. According to the passage, which of the following is an example of a plasma, either real or fictional?

A. The aurora borealis
B. A wild electrical arc
C. Earth's magnetic field
D. Diatium crystals

4. As it is used in line 35, the word convoluted most nearly means:

F. possible.
G. precise.
H. interesting.
J. crazy.

5. If a new crystal were discovered that might make plasma-lightsaber technology possible, how would the author most likely feel about this discovery?

A. Embarrassed and angry at having been proven wrong
B. Excited that his lifelong dream of owning a lightsaber might be about to come true
C. Interested in the new opportunities promised by such a discovery
D. Concerned that such a discovery will detract from the seriousness of the scientific profession

6. The main purpose of the third paragraph (lines 20-33) is to:

F. establish that the author is not in fact an expert in the type of science being discussed.
G. explain in a humorous fashion that the official explanation of lightsabers borders on nonsense.
H. remind the reader of the important difference between science fiction and fantasy.
J. express disdain for the silliness of the Star Wars film series.

7. According to the passage, which of the following would be LEAST likely to be involved in a reallife lightsaber?

A. Crystals
B. Batteries
C. Magnetic fields
D. An ionized gas

8. Which of the following statements about plasmas is accurate, according to information in the passage?

F. They can be directed by magnetic fields
G. They are rarely visible to the naked eye
H. They are typically slow moving
J. They nearly always take up large amounts of space

9. Which of the following is true about the author's attitude toward the Star Wars films?

A. Even by Hollywood standards, they are exceptionally inaccurate in their presentation of science
B. They have an adoring fan base that retains hope in fanciful scientific ideas despite the odds
C. They insult their audience by depicting wildly unfeasible technology with little explanation
D. They have indirectly helped society by making generations of people more enthusiastic about science

10. Which of the following is NOT mentioned in the passage as an obstacle to the creation of a real lightsaber?

F. The difficulty of developing a sufficiently compact power source
G. The practical impossibility of containing a plasma field in a way that renders it small and portable
H. The likelihood that such "blades" would just pass through each other, making dueling impossible
J. The possibility that the plasma blade would not even be able to cut anything