Dispersion of light through a prism and block, changing the incident angle

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There was a question in one of my study materials that asked if you increased the incident angle of white light striking the surface of a glass prism, would the colors disperse less or more. The answer was disperse more. I didn't have an answer because I saw a conflict between the two boundaries. At the first interface, increasing the incident angle increases the angle of refraction. However, by my calculations, this results in a smaller incident angle at the second glass/air interface, and thus a smaller emergent angle. Wouldn't these two effects cancel out. The solutions stated that increasing the incident angle increases BOTH the first and second refracting angles. EDIT: Further research has led me to the idea of minimum deviation whereby the emerging angle decreases first til it hits this minimum deviation where it then starts to increase. However, in regards to the question, how would we know in relation to the incident angle whether we are above or below the minimum deviation. It could be above or below unless specified. My idea of minimum deviation is admittedly murky at the moment, I'm going to read more about it tomorrow, its very late.

Also a second question, I read on some site while searching for the answer to my first question that you get disperion when shining light straight through one of the flat sides of a cube or some other object with parallel sides. I thought that when you shine light through a flat film, the incident angle is equal to the emergent angle? EDIT: Wait a minute, just went scavenging for an answer for this one. The angles of each wavelength of light are the same but moved slightly away from each other right?

Thanks!
 
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  • #2
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Thanks for the post! Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post?
 

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