LCDs apply thin-film transistors (TFTs) of amorphous or

Question

LCDs apply thin-film transistors (TFTs) of amorphous or
polycrystalline silicon sandwiched between two glass
plates. The TFTs supply voltage to liquid-crystal-filled cells,
or pixels, between the sheets of glass. When hit with an
electric charge, the liquid crystals untwist to an exact
degree to filter white light generated by a lamp. This
filtered light shines directly on the viewing screen or, in
the case of projection televisions, is projected through a
small chip that acts as a lens. LCDs that are capable of
producing color images, such as in televisions and
computers, reproduce colors through a process of
subtraction, blocking out particular color wavelengths from
the spectrum of white light until only the desired color
remains. It is the variation of the intensity of light permitted
to pass through the matrix of liquid crystals that enables
LCD displays to present images full of gradations of
different colors.

1. The process through which an LCD monitor displays
different colors is most closely analogous to
< An hourglass partially blocked such that a limited
stream of grains of sand fall into the lower portion
< A series of filters that separate all of the components
of a mixture according to size
< A recording studio soundproofed so that any
performances within are muted to those outside
< A piece of construction paper with outlines of
characters cut out such that a lamp in front of the
paper casts shadows in the shapes of the characters
< An air vent that emits warmer air outside of a building
while an air conditioning system cools the interior of
the building

What is the ans

ChrisLele · Answer

A good way to approach this question is to simplify, in your own words, what what the passage is saying in regards to how LCD-screens create color. The following would suffice:

TFT causes crystals/pixels to twist. Light is then shone on the pixels. The manner in which these pixels twist, and thus “interpret” the light, causes a certain color to be projected on screen.

With the above in mind, we want to find an answer choice that presents an analogous scenario. More specifically, and abstractly, we want to find an answer choice that describes how the size and shape of something creates an effect, e.g. the shape of a pixel corresponds to a certain color.

A. An hourglass partially blocked such that a limited
stream of grains of sand fall into the lower portion

Here the effect is one of degree – fewer sand falls into the lower portion. The position of the sands do not project something unrelated to them, e.g. colors.

B. A series of filters that separate all of the components
of a mixture according to size

A good trap answer. Notice that the passage discusses “filtered light.” This doesn’t make the answer choice correct simply because it mentions filter. Analyzing (B) more carefully, we only have components being sorted. The way in which they are being sorted doesn’t create a certain effect, the way that the twisting of the pixels corresponded to certain colors.

C. A recording studio soundproofed so that any
performances within are muted to those outside

Here we have a negating factor – the soundproofing of the room. Had the music, say the pitch of the tones, caused an effect, this answer choice would be analogous.

D. A piece of construction paper with outlines of
characters cut out such that a lamp in front of the
paper casts shadows in the shapes of the characters

Here the outline (or shape) of the characters corresponds to the shadow cast on the wall. Change the outline and the shape will change. Much as changing how the pixel is twisted will change the color on screen. The Answer.

It can be argued that (D) is not perfectly analogous. The outlines of the figure correspond directly to the shapes cast on the wall. The example in the passage is a little more abstract, i.e. exactly how does the twisting of a crystal lead to a certain color, say orange. Nonetheless, (D) is by far the best answer as it is the only one that present us with a scenario in which the shape of one thing corresponds to the shape of another (outlines in paper correspond the shape of the shadow on the wall).

E. An air vent that emits warmer air outside of a building
while an air conditioning system cools the interior of
the building

This answer choice only deal with two mechanisms that have different effects.

BukrsGmat · Answer

Thanks Chris For your Analysis.

alexanthony813 · Answer

i still don't understand why B doesnt work. If light is being filtered out to create a certain color then basically it is filtering out waves based on frequency or wavelength right? So what is the difference between filtering different parts of a mixture based on size, the fact that size isnt the same as frequency/wavelength is the only difference and that's what makes this an analogy...why would d be the correct answer when no components of the light are being filtered out. this is kind of a confusing question, was this actually made by the GMAC? Thanks in advance to whoever replies to my long comment

Vinayprajapati · Answer

"LCDs that are capable of producing color images, such as in televisions and computers, reproduce colors through a process of
subtraction, blocking out particular color wavelengths from the spectrum of white light until only the desired color remains."

This one is really confusing. I still find B as the correct answer.
Explanation: The white light is made upof VIBGYOR i.e. seven different colors of diff wavelengths. Now blocking of one wavelength means filtering it . This is quite similar to multiple filters (until desired color remains) of different sizes to filter out the undesired size.

LCDs apply thin-film transistors (TFTs) of amorphous or

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