Total internal reflection?

Gluk Schmuck · #1 10-15-2001, 01:14 PM

ok...i know:
The critical angle is the angle of incidence which produces an angle of refraction of 90 degrees.
...but i still don't know why it happens...

so...what i want to know is why 'total internal reflection' happens...

Sydney · #2 10-15-2001, 01:47 PM

It's just obeying the law of light/whatever reflection.

n¹ * sine(ø¹) = n° * sine (ø)
n¹ * sine(øcrit) = nr * sine (90 degrees)

n¹ * sine(øcrit) = n°

sine(øcrit) = n°/n¹°

øcrit = sine-1 (n°/n¹) = invsine (n°/n¹)

I better stop pretending I know what I'm talking about. What is this? Advanced maths? I hate maths.

Teal · #3 10-15-2001, 01:54 PM

Unh. *knows why it works but can't explain it right now*

I'd offer to dig out my old physics notes, but by the time I get back here (tomorrow morning) someone else will have replied.

Hm. No matter, I want to know anyway now, so I might as well go look.

Danny · #4 10-15-2001, 04:27 PM

i don't know, really. i will probably know by this time next year, since i'm doing Physics A-Level, but at the moment we're doing Particle Physics and Electronics. i could tell you the charge of a Strange Quark, if you like... Pion+? Up Quark? Muon?

but no, reflection is out of my field, sorry...

FuzzyFuzzle · #5 10-15-2001, 05:28 PM

I had an internal reflection once...I thought I should stop wasting time playing video games and help make the world a better place...then I started breathing.

Gluk Schmuck · #6 10-16-2001, 04:11 AM

i like your answer Fuzzy...

so...does it happen in a ripple tank???

Danny · #7 10-16-2001, 06:15 PM

i don't think so, i thought it was just a light thing. i mean, the waves do all reflect internally in a ripple tank, but that's just because of the walls, it's nothing to do with refraction.

the only time i've heard TIR mentioned is concerning light and prisms [or other refracting things], when the light enters the prism at the right angle so that it doesn't emerge again. i think... i hope...