<p>Why is it that when a wave (say transverse) passes from a dense medium (say a spring) into a less dense medium, the transmitted wave is not always larger than the original. I'm not sure, but I believe it has to do with the amount of energy in the original wave, or I'm just completely wrong.</p>
<p>Also, why is it that frequency remains constant when a wave changes mediums and is this why speed changes since only wavelength changes?</p>