# Reflection, Refraction, Diffraction

318 Words2 Pages
REFLECTION, REFRACTION, DIFFRACTION Reflection – waves bounce off a surface Refraction – waves bend when they pass though a boundary Diffraction – waves spread out (bend) when they pass through a small opening or move around a barrier REFLECTION - when a wave encounters a barrier, it can reflect the bounce off the obstacle - i.e. light = mirror; sound = echo - most objects we see reflect light rather than emit their own light - Fermat’s principle = light travels in straight lines and will take the path of least time Laws of Reflection 1. The angle of incidence equals the angle of reflection (true for both flat and curve mirrors) 2. The incidence ray, reflected ray, and the normal all lie in the same plane. Specular vs. Diffuse Reflection - in diffuse, waves are reflected in many different ways form a rough surface - in specular, waves are reflected in the same direction from a smooth surface REFRACTION (light) - when one medium ends and another begins, that is called boundary - when a wave encounters a boundary that is denser, part of it is reflected and a part of it is transmitted - the frequency of the wave is not altered when crossing the boundary / barrier but the speed and wavelength are - the change in speed and wavelength can cause the wave to bend if it hits the boundary at an angle other than 90 degrees - this bending as light enters the water can cause objects under water to appear at a different location than they actually are REFRACTION (sound) - sound waves bend when passing into cooler / warmer air because the speed of sound depends in the temperature of the air - sound travels slower in cooler air REFRACTION (water) - water waves bend when they pass from deep water into shallow water, the wavelength shortens and they slow down. DIFFRACTION - involves a change in direction of waves as they pass through