Color Corresponds to the ____ of Light Waves
In this section we explore the pysical characteristics of a wave and consider the nature of light waves and how humans perceive light.
Amplitude and wavelength
Two physical characteristics of a wave are amplitude and wavelength (Figure 5.4). The amplitude of a
wave is the height of a wave as measured from the highest point on the wave (peak or crest) to the lowest
point on the wave (trough). Wavelength refers to the length of a wave from one peak to the next.
Figure 5.4 The amplitude or height of a wave is measured from the peak to the trough. The wavelength is measured
from peak to peak.
Wavelength is directly related to the frequency of a given wave form. Frequency refers to the number of
waves that pass a given point in a given time period and is often expressed in terms of hertz (Hz), or cycles
per second. Longer wavelengths will have lower frequencies, and shorter wavelengths will have higher
frequencies.
Light waves
The visible spectrum is the portion of the larger electromagnetic spectrum that we can see. As Figure 5.6
shows, the electromagnetic spectrum encompasses all of the electromagnetic radiation that occurs in our
environment and includes gamma rays, x-rays, ultraviolet light, visible light, infrared light, microwaves,
and radio waves. The visible spectrum in humans is associated with wavelengths that range from 380 to
740 nm—a very small distance, since a nanometer (nm) is one billionth of a meter. Other species can detect
other portions of the electromagnetic spectrum. For instance, honeybees can see light in the ultraviolet
range (Wakakuwa, Stavenga, & Arikawa, 2007), and some snakes can detect infrared radiation in addition
to more traditional visual light cues (Chen, Deng, Brauth, Ding, & Tang, 2012; Hartline, Kass, & Loop,
1978).
Figure 1. Light that is visible to humans makes up only a small portion of the electromagnetic spectrum.
In humans, light wavelength is associated with perception of color (Figure 5.7). Within the visible
spectrum, our experience of red is associated with longer wavelengths, greens are intermediate, and blues
and violets are shorter in wavelength. (An easy way to remember this is the mnemonic ROYGBIV: red,
orange, yellow, green, blue, indigo, violet.) The amplitude of light waves is associated with our experience
of brightness or intensity of color, with larger amplitudes appearing brighter.
Figure 5.7 Different wavelengths of light are associated with our perception of different colors. (credit: modification
of work by Johannes Ahlmann)
Video Learning
Visible light–red, orange, yellow, green, blue, indigo, and violet–is just a narrow range of wavelengths within the larger electromagnetic spectrum that includes microwaves, radiowaves, x-rays, and infrared radiation.
In this TED-Ed video Lucianne Walkowicz discusses the waves we can and cannot see, the visual system cells that first respond to light, and the concepts of frequency and wavelength.
After you watch the video, complete the Think learning activity which assesses your learning with 4 multiple choice questions and 2 open answer questions. You can also get more information by reading the Dig deeper and the Discuss sections.
https://ed.ted.com/lessons/light-waves-visible-and-invisible-lucianne-walkowicz Light waves: visible and invisible
Color Corresponds to the ____ of Light Waves
Source: https://course.oeru.org/ipsy103/archived-sections/waves-and-wavelength/amplitude-wavelength-light-waves/