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• Waves aren't always reflected
• Waves can either be...

  • absorbed - energy stored
  • transmitted -
  • reflected
• Angle of incidence is always equal to the angle of reflection
• Normal is perpendicular
• Specular reflection is when boundary is flat so normals are in the same direction, creating a clear image
• Diffuse reflection is where the boundary is bumpy so normals will be in all different directions, leading light in different directions
• Refraction of Light Waves: when waves change direction as they pass from one medium to another
• Waves travel at different speeds in different materials
• Different mediums have different densities
• The higher the density of the material, the slower the wave
• More dense medium bend towards the normal
• REFRACTION TOOLS

  Just like mirrors being our reflection tools, lenses are our refraction tools. Typically we assume that lenses are used on light that starts in the air (which is close enough to a vacuum to consider n1=1.00) the light then passes through the lens, and exits back in to the air. With this set up we can simply describe the shape of lenses to know what they do!
• CONVERGING LENSES

  Converging lenses focus light towards a central point (called a focus). They do this mostly through convex surfaces where the middle of the lens is thicker than the edges. Following are some sketches of converging lenses. Notice how all of them have 1-2 convex surfaces and they are all thicker in the center than at the edges.
• CONVERGING LENSES

  These are used everywhere- the lenses in your eyes are converging lenses. Reading glasses are converging. Telescopes, microscopes, and magnifying glasses all use converging lenses.
• DIVERGING LENSES

  Diverging lenses disperse light away from a central point (called a focus). They do this mostly through concave surfaces where the middle of the lens is thinner than the edges. Following are some sketches of diverging lenses. Notice how all of them have 1-2 concave surfaces and they are all thinner in the center than at the edges.
• DIVERGING LENSES

  Diverging lenses are used often as well. The primary place we're going to see them is in glasses for nearsighted folks (such as myself!) , but they are also used often to enhance telescopes, binoculars, and cameras!
• A lens power changes with its curvature
• Convex retracts parallel rays of light inwards to a single point called principle focus
• Convex is the same as converging lens, light ways to converge
• Concave refract parallel rays of light outwards, dispersing the light
• All lens have a principle focus on both sides
• The shorter the focal length, the more powerful the lens will be
• In order to make lens more powerful, lens must be more curved or made of different material
• Images are formed at points where all the light ways from a particular point on an object, appear to come together
• Real Image: light rays actually do come together to form the image. Image could be captured on the screen. Inverted
• Virtual Image: formed when the light rays don't come together where the image appears to be. Virtual rays aren't light rays. Appear to be behind the mirror, actually can't be any rays behind
• Real

  • inverted
  • smaller

  Virtual

  • upright
  • smaller