http://www.ck12.org Chapter 12. Waves and Energy Transfer
The situation changes when the wave is passing from a more dense medium into a less dense medium. As you can
see in the sketch below, when a wave pulse moving in denser medium encounters a media interface to a medium of
less density, the reflected wave is upright rather than inverted.
It is also possible for a mechanical wave to encounter an impenetrable barrier, that is, a barrier which does not allow
any transmission at all. In such a case, the complete wave pulse will be reflected and the reflected wave will be
inverted.
Summary
- When a wave strikes an obstacle or comes to the end of the medium it is traveling in, some part of the wave is
reflected back into the original medium. - The law of reflection states that the angle of incidence equals the angle of reflection.
- The general rule, for mechanical waves passing from a less dense medium into a more dense medium, the
reflected wave will be inverted. - When a wave pulse moving in denser medium encounters a media interface to a medium of lesser density, the
reflected wave is upright rather than inverted. - When a mechanical wave encounters an impenetrable barrier, the complete wave pulse will be reflected and
the reflected wave will be inverted.
Practice
Questions
The following video shows a wave machine in action. Use this video to answer the questions that follow.
http://www.youtube.com/watch?v=YQHbRw_hyz4
MEDIA
Click image to the left for use the URL below.
URL: http://www.ck12.org/flx/render/embeddedobject/82876- What happens to the wave when it is reflected from an open end?
- What happens to the wave when it is reflected from a fixed end?