Science for Kids/Mirrors

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Question
Hi, I have a few questions about mirrors. first off I know how a mirror works, but I want to know why exactly do they reflect they way that they do? Like the metal coating on a mirror, what makes it reflect light and why? also do you know any good thorough experiments that I can do to demonstrate and explain this information? I need several good experiments that i can do over a period of about 2-3 weeks. This is for a science project and im kind of stuck. Thank you so much for your help!

-Danielle

Answer
Hi Danielle,

A mirror has a metal coating on one side.  The metal is usually aluminum or silver.   The metal is very pure so it has no faults when it is chemically adhered to the glass.   This creates a brilliant reflective surface.  This means that any light that "falls"onto its surface is reflected.  The metal does not absorb the light .  The photons of light bounce off of the metal surface.  

This can be demonstrated by taking a flash light an shining it into a mirror.  If you move the mirror you can redirect the light from the flash light in different directions.  Since the surface of the glass is also reflective, you can also demonstrate this by shining the flash lights light at a very acute angle to the mirror the producing two reflected beams that are slightly off set.  The offset is the thickness of the glass.  

If you use a prism you can also create a "rainbow" in the mirror which will reflect on to a wall or other surface.  Shine the flash light into the prism and arrange the mirror so that it catches the light refracting through the prism.  Also note that part of the light is reflected off of the surface of the prism.  Using other mirrors you can capture this light too and send it into the prism as well.  If you have set thing up properly, you could potentially "cancel" some of the light creating dark bands in the rainbow.  This shows that light acts as a wave.  

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Ralph Salier-Hellendag

Expertise

Science Fair Judge for many years and experience with robotics, biology, chemistry, industrial processes, metalurgy and metal forming.

Experience

Science Fair Judge for many years and have helped several students get to state level competition. Most recently 2 of my students received state level awards and one went on to the nationals in Washington DC.

Education/Credentials
BA Archaeology - Anthropology
MA Business Anthropology

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