Refraction: Lenses

• Refraction- the bending of light when it travels from one medium to another of different optical densities.
• The ancient Greeks used the concept of light refraction in their living like using a lens to focus light rays.
• Opaque - does not allow light rays to pass through
• Translucent - allows some light rays to pass through
• Transparent - allows all light rays to pass through
• Examples of opaque - paper, cemented wall
• Examples of transparent - yema wrapper, jalousie glass, clear water
• Examples of translucent - muddy water
• Lens - a transparent material made of glass or plastic that refracts light rays and focuses them at a point.
• Convex lens - thicker in the center than edges
• Convex lens - inverted to upright images
• Convex lens - enlarges or reduced images
• Example of convex lens - magnifying glass
• Convex lens - larger -> close
• Concave lens - thicker edges, thinner center
• Concave lens - also called as diverging lens
• Concave lens - upright images
• Concave lens - reduced images
• Example of concave lens - reading glasses
• Convex lens - farther -> inverted
• Convex lens - also called as converging lens