R-AEPHY-11

Table of Contents

Graph

dude gives a little shout, hits wall and goes all the way back.

Use speed of sound in air at $25 \degree C$
"Assume the environment is $25 \degree C$" (this is "Reasonable" as Dr Waters says)
$\therefore v=346 ms^{-1}$
Now we need either the time or distance, to find the other.
- Recall: $v=\frac{s}{t}$
REMEMBER: If we're gonna hear it, the distance is double the distance from the person and the wall! Because the echo has to return back!!!!

Refraction

When a wave enters a new medium at an angle other than $90\degree$, then it will change direction.
Speed changes, frequency does not change!!!!!, hence since $v=\lambda f$, $\therefore \ \lambda$ much change.

Light

It is constant in a given medium!

In a vacuum it is the fastest thing possible
Decreases in speed with increasing density of medium

Sound

Increases in speed with increasing density of medium

Refraction diagram

PUT WAVEFRONTS HERE! AND ALSO ANGLE THINGS