Standing Waves Lab:

Wear and Tear in the Stretchy String: Imagine that some parts of the white string have become a bit frayed and lost their outer coating in certain areas. This topic includes $2$ parts, with each accounting for $10$ pts$.$

Boundaries Between Sections of String: Imagine the coating on the string is very thick $($making up most of the string's mass$),$ and you send a wave from the thicker coated section to the lighter uncoated section. At this boundary, the end of the thick section would behave as if it's almost free $($since it's much easier to move the super$-$light uncoated string$).$ The question is: what happens to the wave when it reaches this boundary?

Boundaries Between Sections of String: It's the same question as before, but now you're considering a wave moving from the uncoated $($lighter$)$ section of the string toward the coated $($heavier$)$ section. This means the wave is entering a region where the string is much heavier, so instead of the end behaving as if it's "almost free," it will behave as if it's "almost fixed." What happens to the wave at this boundary?

Hints:

First, google wave reflection, then you can find many nice graphs showing this. The question should be clear if you look at the graph. You need to answer the following questions for the full credits.

How does the amplitude of the incident and reflected wave behave or change? The amplitude is basically a signal of the energy.

How about the phase?

What about the resultant wave? In other words, which one creates a standing wave in the limit that one is extremally light and the mass is all on the other part of the string? And why? Search for half wave loss.