Hello you wonderful noodle! Can someone please tell me what light source to use when measuring [angle of refraction]? I would use a phone's flashlight, but it spreads the light everywhere, instead of a straight line, and I don't think I have a genuine flashlight anywhere.. Hehe kinda embarrassing, but.. yeah! Thanks! :-)

hey! Quit shining that light in my eyes!

Haha Very funny oobleck ;-) But seriously, do you know what I could use?.. hhaaha

no idea. You say

Can someone please tell me what light source to use when measuring this?

measuring what?

I already said in the title, but it's measuring Angle of Refraction, but that isn't very important, I just need an alternative light source that is in a straight line, unlike my phone's flashlight, also I don't have a flashlight sooo... ya. Or show another way to measure?

So go borrow a flashlight.

cover the lens with a piece of paper.
Poke a hole (or make a slit) in the paper.
The light beam will now be a suitable ray.

even better, borrow a laser pointer.

even better, buy your own. They can be useful items to have.

I'll bet youtube has several videos showing how to do this.

Thanks for the useful idea, oobleck! I'll use that. Thanks again! :-) Have a great summer BTW.

also lazer for the cats