1. DIFFRACTION & REFRACTION OF WAVES

2. DIFFRACTION OF WAVES Diffraction: A change in direction or bending of waves as they pass through an opening or around a barrier in their path.

3. DIFFRACTION OF WAVES - WAVELENGTH Smaller λ = Less Diffraction Larger λ = More Diffraction Wavelength: The smaller the wavelength, the less diffraction will occur. (The sharpness of the bending will be less)

4. DIFFRACTION OF WAVES – THROUGH AN OPENING Opening in a Barrier: The smaller the opening, the greater the diffraction. The larger the opening, the less diffraction

5. DIFFRACTION GAP SIZE

6. DIFFRACTION OF WAVES – TWO OR MORE OPENINGS Diffraction creates circular waves which interfere with each other. Constructive interference where 2 crests meet

7. REFRACTION OF WAVES Refraction: A change in the direction of waves as they pass from one medium to another, or of water waves as they encounter a depth change

8. REFRACTION OF WAVES The diagram shows how waves are refracted and how the velocity and wavelength change. Recall that as waves enter a medium with differing properties, the velocity will change. As water encounters a depth change, the velocity will change. V 2, λ 2 V 1, λ 1

9. REFRACTION OF WAVES - CALCULATIONS Remember this sucker? v = fλ The waves are from the same source so f is constant If λ increases, v must increase (and vice versa) If λ decreases, v must decrease (and vice versa) This relationship comes back to help us again:

10. REFRACTION OF WAVES – EXAMPLE CALCULATION A water wave has a wavelength of 5.0 cm in a shallow section of water. It encounters a depth change, its wavelength increases to 8.0 cm, and its velocity increases to 2.0 m/s. What was its original velocity?