A wave is a disturbance that moves along a medium from one end to the other. The crest is observed to what is ripple frequency distance.
If the crest of an ocean wave moves a distance of 20 meters in 10 seconds, then the speed of the ocean wave is 2. The faster wave travels a greater distance in the same amount of time. Sometimes a wave encounters the end of a medium and the presence of a different medium. For example, a wave introduced by a person into one end of a slinky will travel through the slinky and eventually reach the end of the slinky and the presence of the hand of a second person. One behavior that waves undergo at the end of a medium is reflection.
The wave will reflect or bounce off the person’s hand. Reflection phenomena are commonly observed with sound waves. When you let out a holler within a canyon, you often hear the echo of the holler. Noah stands 170 meters away from a steep canyon wall. He shouts and hears the echo of his voice one second later. What is the speed of the wave?
Remember, when there is a reflection, the wave doubles its distance. In other words, the distance traveled by the sound wave in 1 second is equivalent to the 170 meters down to the canyon wall plus the 170 meters back from the canyon wall. Variables Affecting Wave Speed What variables affect the speed at which a wave travels through a medium? Does the frequency or wavelength of the wave affect its speed? Does the amplitude of the wave affect its speed? Suppose a wave generator is used to produce several waves within a rope of a measurable tension.
The wavelength, frequency and speed are determined. Then the frequency of vibration of the generator is changed to investigate the effect of frequency upon wave speed. Finally, the tension of the rope is altered to investigate the effect of tension upon wave speed. Sample data for the experiment are shown below.
In the first five trials, the tension of the rope was held constant and the frequency was systematically changed. The data in rows 1-5 of the table above demonstrate that a change in the frequency of a wave does not affect the speed of the wave. The speed remained a near constant value of approximately 16. The last three trials involved the same procedure with a different rope tension.
Observe that the speed of the waves in rows 6-8 is distinctly different than the speed of the wave in rows 1-5. The obvious cause of this difference is the alteration of the tension of the rope. The speed of the waves was significantly higher at higher tensions. Waves travel through tighter ropes at higher speeds. One theme of this unit has been that “a wave is a disturbance moving through a medium.