A would be the wavelength, C would be a crest, D would be the amplitude, leaving B which is the trough.
Answer:
its an antique physics apparatus for demonstrating acoustic standing waves in a tube.
Answer:
It will have aim at a point "below" the insect.
From the insect's point of view, the fish will appear to be shallower than it actually is because a ray of light from the insect to the fish will be bent "towards" the normal when the ray enters the water
