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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.
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.
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Analyzing Data What is the difference between wave C and wave D in the figure?
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.
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Inferring Compare the two waves in the figure. To what in wave B do the compressions of wave A correspond? To what in wave B do the rarefactions correspond?
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The force that caused wave A added more energy to the wave than the force that caused wave B.
Comparing and Contrasting The figure shows how someone starts the waves. How are these ways of starting waves alike? How are they different?
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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.
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Wave D has a frequency twice that of wave C; Therefore, the wavelength in wave D is one half that of wave C.
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Inferring In the figure, 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?
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Inferring What represents one wavelength in wave A of Figure 17-2? Define and describe the portion of the wave.
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A; Longitudinal
B; Transverse
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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.
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Interpreting Illustrations What kind of wave does A in the figure represent? What kind of wave does B represent?
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Wave B has an amplitude that is one half the amplitude of wave A.
Drawing Conclusions Consider both frequency and wavelength in the figure. 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 same speed.
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Analyzing Data What is the difference between wave A and wave B in the figure?
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Between wave C and wave D, frequency doubles, but wavelength is halved. Wavelength is inversely proportional to frequency.
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In reflection, a wave hits a solid barrier that it cannot penetrate, so it reflects, or bounces back, in roughly the same direction from which it came. In refraction, a wave hits a change in the medium, but instead of reflecting (bouncing back), it continues on into the new medium, bending as its speed changes.
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In a large cave, you can hear an echo a few seconds after you speak. Explain how this happens in terms of wave properties.
Explain the difference between reflection and refraction.
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Sound waves, like other kinds of waves, reflect, or bounce back, when they strike a solid barrier. It takes time for the echo to return, traveling at the speed of sound, so there is a delay.
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