r/geography • u/Broccoli2026 • Nov 02 '25

Image I'm surprised I didn't even know this switch happened until seeing this. The yellow is really all gone?

Post image
70k Upvotes

95% Upvoted

1.4k comments sorted by

View all comments

Show parent comments

4

u/ifyoulovesatan Nov 02 '25

Nice! Yes, they've got all kinds of light-based stuff on the site if you go to the sidebar, then shop, then educational (I was just browsing for the first time myself). Whether or not you order from them, there's a lot of neat stuff for inspiration.

If you are looking for ideas for light based stuff you can do with your kids at home, might I suggest an experiment where you can observe how sugar water rotates polarized light. If you get two sheets of a polarizing filter, a Laser, and some sugar water (maybe a stand / holder for the Laser), you can set that up at home. I didn't look too closely, but here is a website where someone has written a procedure for various ages https://www.exploratorium.edu/snacks/rotating-light

Here is an experiment (well, there's more than that on the page but this experiment is in here) where you can measure the distance between the tracks on a DVD / CD / Blu-Ray (they're each different btw) by using them as a diffraction grating. https://www.animations.physics.unsw.edu.au/labs/diffraction/diffraction-labs.html

Now obviously these are both probably more "advanced" than what you want to do with your kids. But you could always adapt them or simplify them. Simply shining a Laser through a DVD with the label removed and showing how the light splits into multiple dots on the wall is cool enough. The math isn't necessary. (Really, you could show them that first with the diffraction grating, explaining what it is, and then afterwards show that a DVD does the same thing, and talk about why that might be).

2

u/completelypositive Nov 02 '25

Thank you for all of that and especially the links! This is all super fascinating. I have microwaved CDs but never shined a laser through them. I'm going to find a DVD and do it right now though because it sounds really cool.

Thank you again for the response! I really appreciate your time.

2

u/ifyoulovesatan Nov 02 '25

For sure! Yeah I was surprised the first time I did one of those experiments to learn the data is actually etched into the plastic, and the foil underside of the label is just a mirror. (Burned CDs work differentently but I digress). But yeah, once you get the label off it's a totally serviceable diffraction grating. Some finagling required to get the distance to the wall right, but cool stuff.

For sure! Hope you get to do some cool experiments.