Monochromatic light and reflection

[okgo]

http://www.screencast.com/users/trinhn812/folders/Jing/media/07c73e88-45a9-4703-91e1-237b20135d2c

I'm not sure why the answer is A. I tried reasoning myself that it has to do with the critical angle, but I can't seem to convince myself.

 

[Stickey]

Perhaps just a geometric problem?

 

[okgo]

so perhaps the index of refraction does not matter?

 

[Stickey]

From that question, I wouldn't say so .. I assumed it continued to asking something else later on, more relevant to the refractive index?

 

[okgo]

lol no. This was a practice exam and half the people got it wrong. I guess the teacher was just being tricky.

 

[Stickey]

Very sneaky!

Well, from how it reads, I'd say that's the right answer

 

[ehild]

Think of phase change at both boundaries: air-alcohol and alcohol-plastic. What is the phase difference between the wave reflected from the alcohol-plastic interface and the directly reflected one (from the air-alcohol interface)?

ehild