Michigan Test for Teacher Certification (MTTC) Secondary Integrated Science Practice test

Which statement about boundary behavior is true?

1. Wave frequency changes when crossing a boundary

2. Wave speed is less in less dense mediums

3. Amplitude of the incident pulse is always greater than that of the reflected pulse

4. Wavelength decreases in more dense mediums

The correct answer is: Amplitude of the incident pulse is always greater than that of the reflected pulse

The correct statement regarding boundary behavior is that the amplitude of the incident pulse is always greater than that of the reflected pulse, specifically in scenarios involving certain types of boundaries, such as fixed boundaries. This phenomenon occurs due to energy conservation; when a wave encounters a boundary, some energy is transmitted into the new medium while some is reflected back. The reflected wave may have a lower amplitude than the incident wave depending on the properties of the boundary and the media involved, particularly when an elastic medium reflects a wave. In this context, if the boundary is fixed, the wave reflects with an inversion and this reflection also affects the amplitude. Thus, it's common to observe that the incident amplitude is not just larger but serves as a reference point to show how the energy is distributed over the waves. On the other hand, wave frequency generally remains constant when crossing boundaries, so the statement about wave frequency changing is not accurate. Wave speed can actually increase in less dense media, contradicting the notion that it is less in those conditions. Lastly, wavelength does not strictly decrease in more dense mediums; it can change depending on multiple factors including the wave speed and frequency, but isn’t necessarily always tied to density alone. Understanding these concepts helps grasp the intricacies of wave