# To all at PFs

1. Dec 23, 2016

### wolram

Have a happy and peaceful holiday

2. Dec 23, 2016

### dkotschessaa

OH - SIN THETA-ONE TIMES INDEX ONE
(Melody: God Rest Ye merry, Gentlemen)

Light travels in straight lines,
that is unless somehow it's turned.
It can reflect (or bounce right back),
But that's quite eas'ly learned.
Refraction is the property
with which we're now concerned:

Chorus:
Oh - Sin theta-one times index one
is equal to
Sin theta-two times index two!

Refraction is the bending
which is caused by changing speed.
When entering at an angle,
light will bend, and then proceed--
to travel in a new straight line,

Oh - Sin theta-one times index one
is equal to
Sin theta-two times index two!

Now since the bending's caused by changing speed, we have a clue
To calculate light's speed in any medium, (it's true!)
n-one v-one is equal to n-two times v-two.

Oh - Sin theta-one times index one
is equal to
Sin theta-two times index two!

When slowing down the light bends 'toward the normal' as they say.
When speeding-up it will bend from the normal away --
Until the angle critical is reached to our dismay!

Oh - Sin theta-one times index one
is equal to
Sin theta-two times index two!

(Source: http://www.wesleyan.edu/physics/fun_stuff/physics_carols.html#1a)

3. Dec 23, 2016

### OmCheeto

Ah! Hahahaha!

4. Dec 23, 2016

### dkotschessaa

@OmCheeto Yeah. I LOLed when I saw that one and then realized that would have been a better one to post.