General properties of waves — Describe

How do waves undergo (a) reflection at a plane surface, (b) refraction, and (c) diffraction through a narrow gap?

(a) Reflection: waves bounce back off a plane surface, with the angle of reflection equal to the angle of incidence, and speed and wavelength unchanged. (b) Refraction: waves change speed as they cross a boundary into a different medium, causing a change in wavelength and, if the wave meets the boundary at an angle, a change in direction; frequency stays the same. (c) Diffraction: waves spread out after passing through a narrow gap, with the spreading being greatest when the gap is similar in size to the wavelength.