PrepTest 151, Section 2, Question 17
Increasing the electrical load carried on a transmission(56 more words not shown)
Which one of the following(8 more words not shown)
- AElectrical utility companies(20 more words not shown)
- BTransmission lines that(24 more words not shown)
- CThe electrical load(18 more words not shown)
- DAir temperature has(13 more words not shown)
- EThe maximum operating(14 more words not shown)
Reading the argument
The line has two forces pulling its temperature in opposite directions: electrical load heats it, while wind cools it.
More load can push it past its operating limit. Stronger wind provides more cooling, and wind across the line cools it more than wind running along it. Parallel wind can still cool the line; it just does less than a crosswind.
What we’re looking for
There isn't an argument to attack here. We're asked what these facts support. Combining the heating and cooling effects, I'd expect stronger cooling to let the line carry more electricity before it gets too hot.
Working the answers
- A
Being able to carry more electricity doesn't tell us what utility companies typically choose to do. They might keep the load unchanged because demand hasn't risen, for example. The passage describes what affects the line's temperature, not companies' operating decisions on windy days.
- B
This has the wind direction backward. Wind blowing across a line cools it more than wind blowing parallel to it. For otherwise identical lines exposed to the stated winds, the greater cooling advantage belongs to the line at a right angle to the wind, not the parallel line. B assigns the greater load capacity to the wrong one.
- CCorrect
Increasing wind speed cools the line more. That cooling leaves more room for the heating caused by a larger electrical load before the line reaches its maximum operating temperature. C combines the two effects the passage gives us; it doesn't require a separate claim about utility-company behavior.
- D
We aren't given a comparison between air temperature and wind speed. Knowing that wind matters doesn't tell us whether another factor matters more or less. D adds a ranking of influences that the passage never establishes.
- E
The wind changes the line's actual temperature, not the maximum temperature at which it is supposed to operate. Imagine a hypothetical line with a fixed operating limit of 30 degrees. More cooling could let it carry a larger load while staying below 30; it wouldn't turn the limit into 35. The increased capacity concerns electrical load, not a new temperature ceiling.
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