Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: thedoc on 02/10/2013 04:30:02

Title: What causes a reflection?
Post by: thedoc on 02/10/2013 04:30:02
"rokeyakarolia asked the Naked Scientists:
   I'm having difficulty understanding how to differentiate between the different types of reflection.

My son and I have chosen to do an experiment on reflection of light, which involves shining a laser torch light in a dark room onto a CD....

It does cause a reflection on the wall and ceiling and looks like something from a Jean Michelle Jarre sound and light show, minus the sound...

I don't know if this actually is appropriate to his topic of "what causes reflection". and thus I can't explain to him what is actually happening...

Kindly let us know if we are pursuing the right direction or if not please can you guide us to something more appropriate...

Thanking you in advance...

Let me thank you for a wonderful demo. on how much fun science actually is during the Rand Show expo in South Africa. My 9 yr. old son thoroughly enjoyed it.

Rokeya Karolia
Johannesburg

What do you think?
Title: Re: What causes a reflection?
Post by: RD on 02/10/2013 06:12:10
The multi-colours are due interference  ...

Quote from: wikipedia.org/wiki/Interference_(wave_propagation)
(https://upload.wikimedia.org/wikipedia/commons/thumb/3/39/Interferenz_bei_der_Lichtreflexion_an_einer_CD.jpg/220px-Interferenz_bei_der_Lichtreflexion_an_einer_CD.jpg)
interference caused by the reflection on a CD
https://en.wikipedia.org/wiki/Interference_%28wave_propagation%29

The grooves on the CD act like a diffraction grating (https://en.wikipedia.org/wiki/Diffraction_grating#Examples).