The color of things is determined by what wavelengths are reflected by the object and what wavelengths are absorbed. If you shine a red light on a red object, it will reflect the incident red light backatcha. if you shine a blue light on a red object, it won't reflect any light. So, it will appear un-illuminated.
The sun produces white light - which contains all the wavelengths - thus a prizm will show a complete rainbow in sunlight.
Optics in general are quite interesting. An image that is seen thru a magnifying lens will be inverted. So, given the number of lenses in series you can create big right-side up, images of things that are microscopically small or large, but far away. I wonder how those early telescope grinders figured out what to do. I bet it was fun to get a detailed image of the moon the first time.
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http://www.physlink.com/education/askexperts/ae353.cfm
If you shine a red light on a red object, it will reflect the incident red light backatcha.
if you shine a blue light on a red object, it won't reflect any light. So, it will appear un-illuminated.
The sun produces white light - which contains all the wavelengths - thus a prizm will show a complete rainbow in sunlight.