Reflection and refraction

• Are waves always reflected?

  No, when a wave hits a boundary, three different things can happen. It can be absorbed, reflected, or transmitted. Whichever one happens depends on the wavelength and the properties of the two materials.
• What rule is used when making a ray diagram?

  The angle of incidence is equal to the angle of reflection.
• What does it mean if the boundary is flat?

  All the normals are in the same direction, all the incoming light rays will be reflected in the same direction. This is called specular reflection and it creates a clear image.
• What does it mean if the boundary is bumpy?

  The normals will all be different because the surface is not flat, meaning light will be reflected in different directions. This is called diffuse/scattered reflection, meaning you can't see your reflection in these materials.
• What does specular and diffuse/scattered reflection have in common?

  Both of their angle of incidences are equal to their angle of reflection
• What happens during the refraction of light waves?

  Waves change direction as they pass from one medium to another.
• What happens to waves in different materials?

  They travel at different speeds in different materials. This is because different mediums have different densities. The higher the density of the material, the slower the wave.
• What happens when the wave travels perpendicular to the boundary?

  It will continue straight on through the more dense material, no refraction occurs.
• What happens when white light is shone through a triangular prism?

  The white light contains red, orange, yellow, green, blue, indigo, violet which are all refracted by different amounts when the white light is shone through the prism, the colours bend to different degrees.