Digital PSAT Reading and Writing Practice Question 193: Answer and Explanation

Question: 193

Electromagnetic Waves and Their Wavelengths

Wave Type

Wavelength in Meters

Gamma

1 × 10-11

X-ray

1 × 10-9

Ultraviolet

2 × 10-8

Infrared

1 × 10-6

Radio

1.0

The brain's integration of photons allows humans to perceive colored light with wavelengths between roughly 400 and 700 nanometers (a billionth of a meter), which comprises the entire visible spectrum.

Based on the information in the above text and in the table, light visible to humans would have wavelengths between which two types of waves?

  • A. Gamma and X
  • B. X and ultraviolet
  • C. Ultraviolet and infrared
  • D. Infrared and radio

Correct Answer: C

Explanation:

(C) The text states that humans are visibly able to perceive wavelengths between 400 and 700 nanometers. (A) nanometer is 1 × 10-9 meters, so the visible wavelengths would fall between the ultraviolet and infrared wavelengths.

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