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Asked by to Sabina, Paul, Mike, Matthew, Mark on 11 Mar 2014. This question was also asked by .
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Matthew Malek answered on 11 Mar 2014:
Reflection: “The angle of incidence equals the angle of reflection.” That’s the single most important thing to remember when working with reflection. Basically, the angle before striking the reflecting surface (call it “theta_1”) is equal to the angle after leaving that surface (call it “theta_2”).
Easy, yes? But a bit dull, too.
Refraction gets a bit more interesting, with Snell’s Law telling us that these angles are related by:
sine(theta_1) / sine(theta_2) = speed in medium 1 / speed in medium 2
Does that make sense? If not, leave a comment or ask another question and I’ll clarify further!
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Paul Coxon answered on 11 Mar 2014:
The physics of reflections is a really interesting research area. It’s very important, without reflections we wouldn’t be able to see the world around us.
In my work I’m investigating ways to minimise reflections from various new materials so that solar panels can work at higher efficiency. Any reflected light is wasted light which could be converted into electricity.
There are two main types of reflection: diffuse reflection and specular reflection.
Normally, light itself is invisible until it undergoes reflection from a surface and reaches our eyes. Eg a beam of light from a torch can’t be seen from the side until it interacts with something that scatters it, like a dust particles in the air. This scattering is diffuse reflection and happens when light is reflected from a rough surface. This is important, because the majority of light reaching our eyes from the world around us has been reflected in this way. The eyes and brain use this reflected light to help judge the appearance, textures and depth of the objects around us.
Light hitting a smooth surface like a mirror undergoes specular reflection where nearly all of the incident light is reflected back in a single direction. Highly polished objects often cause specular reflection which makes them appear shiny.
If you need to know any more, just drop a comment below.
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Mark Jackson answered on 12 Mar 2014:
I always thought it was strange that my reflection flipped left and right, but not top and bottom.
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Mike Lee answered on 12 Mar 2014:
When light hits something, two types of reflection can happen. Either it moves off in all directions, or in one particular direction.
Look at your hand. Then look at your hand from another direction. Can you still see your hand? If the answer is “yes” then the reflection is happening.
Look at a mirror. Make a note of what you can see. Then look at the mirror from a different direction. If you can no longer see what was there, it must be the second type of reflection.
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