1. Reflection and Refraction

2. Bouncing Wave • The medium for waves is not always uniform. • Extreme case is for a collision with a barrier A single pulse is reflected back in the opposite direction.

3. Open Ended • The medium may end in air. • Extreme case the end is loose and completely free A single pulse is reflected back in the same direction.

4. Mixed Media • The medium may change. • A thin rope attached to a thick rope Part of the pulse is reflected but part is transmitted.

5. Waves can be seen as sets of parallel lines moving forward. Wave fronts May be curved A ray follows a point of successive wave crests. Perpendicular to front Straight until a barrier is reached Ray Tracing

6. Perfect Mirror • Larger waves also interact with barriers. We can follow a line perpendicular to the wave front. • These are called rays • A reflected ray has the same angle after reflection. • Angle qi = qr

7. Rough Shoulder • A car approaches a sandy shoulder from pavement. • The wheels that hit the shoulder slow down • An angle causes the car to turn into the shoulder

8. Refraction • As a wave changes its medium the speed changes, and so does its wavelength.

9. Snell’s Law • For plane waves the angles are related to the speeds in the two media. • This is called Snell’s Law next