Chapter 11.3-11.4 Section Reviews

11.3 Properties of Waves 1. The disturbance is transmitted through the water (medium) as wave energy. 4. If the amplitude increases by a factor of four, then the energy increases by 16 times. See wave speed problems solution from page 387 for answers to questions 2, 3 and 5

11.4 Wave Interactions 1. The largest resultant displacement for two waves of .2 and .3 m is 0.50 m. 2. If ends are fixed, the maximum amplitude for these two waves is 0.0 m because the pulse will invert when reflected. This is an example of destructive interference. 3. If ends were free, the maximum amplitude for these two waves is 0.30 m because the pulse will reflect but will not invert. This is an example of constructive interference. 4. Three wavelengths produced on a fixed string 2.0 m long are 4 m (2L), 2 m (L) and 1.3 (2/3 L) 5. 4 nodes, 3 antinodes

Transverse Waves A wave in which the particles move perpendicular to the direction the wave is traveling The displacement-position graph below shows the wavelength () and amplitude (A). Ask students to draw the wave on the left, and to identify in their diagrams the directions of wave motion (a horizontal line) and particle motion (a vertical line). Point out to students that, even though the graph on the right looks like the wave, it is really the measured values for displacement as a function of position. This is important because a subsequent slide will show a longitudinal wave and a graph of density-position, and that graph does not look at all like the wave. Instead, it looks like a transverse wave. It is important that students understand what is being graphed, and that graphs are mathematical models rather than pictoral representations.

Longitudinal Wave Chapter 11 Section 3 Properties of Waves