Download Geometric Optics: Reflection and Refraction of Light - Prof. Brian N. Espino and more Study notes Physics in PDF only on Docsity! Geometric Optics Light travels in straight lines (rays) unless the light encounters some change in medium. When the light reaches a change in medium two actions my occur. reflection refraction Sometimes both occur (Remember, light travels as a wave and these are wave properties.) examples: light reflecting off of a mirror sunlight, the reflection of a street light off of a puddle light refracting as it travels through a prism. Law of reflection When light reflects off of a surface, the angle the incident light makes to a line perpendicular (normal line) to the surface is the same angle the reflected makes to the normal line. angle of incidence ( i) = angle of reflection ( r) incident ray reflected ray normal line surface i r example of refraction When light goes from air to water it refracts (bends). The picture on the right shows why the straw appears bent. Example of reflection and refraction occurring. Quite often light undergoes both reflection and refraction. Here light passes from air to glass then back to air. incident ray reflected ray refracted ray glass air air Application of refraction Lenses: By taking advantage of the bending of light as it passes through a lens, people can control the path that light takes. two types of lenses: converging lens, diverging lens Converging lens takes rays and focuses them to a point. Diverging lens causes the rays to spread out. Converging lens.
Positive (converging) lens
Ray tracing rules 1) If ray comes from parallel to axis, after being refracted, it will pass through the focal point. 2) If ray is drawn through the center of the lens, it keeps going straight. 3) If ray is drawn through the focal on the same side of the object, after going through the lens, it will be parallel to the principle axis. 1 2 3 Ray tracing for Spherical mirrors 1) Rays drawn parallel to principle axis are reflected through the focal point. 2) Rays drawn through focal point are reflected parallel to principle axis. 3) Ray drawn through center of curvature (point C) get reflected back on itself. 4) Also can see that a ray incident at the center of the mirror is reflected at an equal angle. Play around with website to see what happens when you move the object around. http://physics.bu.edu/~duffy/semester2/c25_sp herical.htm http://www.physics.brocku.ca/Courses/1P22_Cr andles/applets/Mirrors/
