<span>supply it with more energy. one way to do is to produce vibrations in the same frequency as the wave. This would cause resonance leading to higher amplitude</span>
A wave that is oscillation of matter.. such as a water ripples
The slope of the line ... or the direction it's heading ... is the speed
of whatever is being graphed. So if the line changes direction, it
means that the speed changed at that time.
When a ray passes from air into glass the direction in which the light ray is travelling changes. The light ray appears to bend as it as it passes through the surface of the glass. When a light ray passes from air into water a similar thing occurs: the light ray is bent as it strikes the surface of the water.