Name: Date: Block:
ACT Prep: Waves
USING SCIENCE SKILLS
1. Interpreting Illustrations What kind of wave does
A in Figure 17-2 represent? What kind of wave does
2. Comparing and Contrasting Figure 17-2 shows how
someone starts the waves. How are these ways of
starting waves alike? How are they different?
3. Inferring Compare the two waves in Figure 17- 2.
To what in wave B do the compressions of wave A
correspond? To what in wave B do the
4. Inferring What represents one wavelength in wave A of Figure 17-2? Define and describe the portion of the
5. Using Analogies In Figure 17-2, wave A is produced by a spring toy, representing the concept of a sound wave in
air. In sound, what is being squeezed together in the compressions, and what is being released in the rarefactions?
6. Analyzing Data What is the difference between wave A
and wave B in Figure 17-3?
7. Inferring In Figure 17-3, both wave A and wave B
were started by the same type of force—an up-and-
down motion. What conclusion can you make about the
energy of these two wave-starting forces?
8. Predicting Suppose you add the following panel E to the
diagram: a wave pattern with a frequency of four
waves per second. How will wavelength in this panel
compare with the wavelength in panel D? How will it
compare with the wavelength in panel C? Assume all the
waves travel at the same speed.
9. Analyzing Data What is the difference between wave C
and wave D in Figure 17-3?
10. Drawing Conclusions Consider both frequency and wavelength in Figure 17-3. How does each variable change
between wave C and wave D? What is the relationship that explains the change? Assume the waves travel at the
USING SCIENCE SKILLS
11. Comparing and Contrasting Which waves in Figure 18-2 carry AM and FM signals? How do the frequencies of
AM and FM signals compare?
12. Analyzing Data How does photon energy change with increasing frequency? Use Figure 18-2 to answer this
13. Interpreting Graphics Which waves in Figure 18-2 are used to expose heat-sensitive film? Where are these
waves located in the electromagnetic spectrum?
14. Classifying In Figure 18-2, which waves can be separated into different wavelengths of colored light?
15. Inferring Look at Figure 18-2. Without referring to the specific frequencies and wavelengths of the colors of the
visible spectrum, at which end of the visible spectrum would you place red? At which end would you place
violet? Hint: Use the names of the waves outside the visible spectrum to help you.
Answer Section: Waves
a longitudinal wave; a transverse wave
Both waves are started by application of a force. However, wave A, the longitudinal wave, is started by a back-
and-forth, or push-and-pull, movement in the same direction as the resulting wave movement, while wave B, the
transverse wave, is started by an up-and down movement that is at right angles to the resulting direction in which
the wave travels.
Compressions in wave A correspond to crests in wave B. Rarefactions in wave A correspond to troughs in wave
B. Each of these conditions represents an extreme in which the coil is being displaced from its rest position.
In wave A, one wavelength equals the distance between center of a compression in the spring toy and the
corresponding location in the next compression. Wavelength is the distance between a point on one wave and the
same point on the next cycle of waves.
In a sound wave in air, the compressions consist of regions of bunched-up air, while the rarefactions consist of
regions in which the molecules are more spread out.
Wave B has an amplitude that is one half the amplitude of wave A.
The force that caused wave A added more energy to the wave than the force that caused wave B.
The wavelength in E will be one half that of the wavelength in D; it will be one fourth that of the wavelength in C.
Wave D has a frequency twice that of wave C; Therefore, the wavelength in wave D is one half that of wave C.
Between wave C and wave D, frequency doubles, but wavelength is halved. Wavelength is inversely proportional
Radio waves; FM signals usually have higher frequencies than AM signals have.
High-frequency waves such as X-rays and gamma rays have higher energy photons than lower-frequency waves
such as radio waves and infrared rays.
infrared rays; between visible light and microwaves
Red would be at the end of the visible spectrum with the lowest frequency and longest wavelength of all the
colors, just above the infrared range. Infra- means “under,” so infrared- means “under red.” In the same way,
ultra- means “beyond,” so ultraviolet means “beyond violet.” Violet would be at the end of the visible spectrum
with the shortest wavelength and the highest frequency.