waves

• transverse = oscillations are perpendicular to the direction of energy transfer
• longitudinal = oscillations are parallel to the directions of energy transfer eg sound waves
• specular reflection = wave reflected in a single direction by a smooth surface
• diffuse reflection = reflection from a rough surface which causes scattering
• optical density = how quickly light can travel through it - more dense, the slower waves travel through it
• less dense (air) to more dense (glass) light bends TOWARDS the normal
• refraction = due to the difference in velocity of the waves as they pass through a boundary