Why Does Light Interference Differ from Sound Interference?

[Janiceleong26]

Homework Statement

Homework Equations

I α A²

The Attempt at a Solution

My teacher told us that if the source is a light source, then the answer would be B, why? Why would the intensity be the same for each maxima? And zero intensity when at minima? I thought its amplitude will decrease as it travels further, which means one wave have a larger amplitude than the other, just like this situation. So intensity of each maxima should decrease just like sound I assume..And the graph should look like D as well (the answer for this question is D)

 

[haruspex]

I don't think any of the pictures are really accurate. it's a bit tricky because the overall picture will depend on how the distance between the speakers compares with the wavelength.
Also, it's unclear whether you are supposed to consider what happens beyond the closest approaches to the two speakers. X and Y do seem to be a bit further out, but as you go out there the minima will get deeper, not shallower.
But to answer your question, I do not know why your teacher says the graph for (coherent) light sources would be different.

 

[Janiceleong26]

I don't think any of the pictures are really accurate. it's a bit tricky because the overall picture will depend on how the distance between the speakers compares with the wavelength.
Also, it's unclear whether you are supposed to consider what happens beyond the closest approaches to the two speakers. X and Y do seem to be a bit further out, but as you go out there the minima will get deeper, not shallower.
But to answer your question, I do not know why your teacher says the graph for (coherent) light sources would be different.

I see, thanks for your time