Optics

• What is Light?

  Light is a form of energy which is emitted or radiated from a luminous body.
• How does light travel?

  Light travels in straight lines. In diagrams, the lines that are used to show the path that light takes are called rays .
• What are diverging beams?

  When all light beams scatter in different directions from a common source.
• What is a parallel beam?

  A beam in which all rays are parallel to one another.
• What is a converging beam?

  When all light rays meet at a common point.
• What are these rays doing?

  
• • Light is a form of *energy  that is transferred as a wave. 
  • As well as being able to travel through *solids , *liquids  and *gases , light waves can travel through a *vaccum .
• Light waves are produced by hot objects, such as the *sun , light bulbs and certain chemical reactions.
• Bioluminescence is the process whereby living things can produce light in their body.

  Marine creatures like some fish, squid, tiny crustaceans and algae produce bioluminescence to either confuse predators, attract prey or even lure potential mates.

   
• What is the speed of light in a vacuum?

  3x10(to the power of 8) metres p/second
• Light can pass through translucent and transparent objects
• When travelling through denser mediums, the speed of light slows down.
• When travelling through lighter mediums the speed of light increases.
• When light enters a denser medium it bends away from the normal.
• When light enters a lighter medium it bends towards the normal.
• Absorbed

  When light rays are taken in by an object
• Reflected

  When light rays bounces off an object
• Refracted

  When light rays are transmitted from one medium to another and change direction due change in speed of light
• Direct transmission


  When light travels straight through an object
• Diffuse transmission

  When light scatters as it travels through an object
• Transparent

  A type of object in which all of the light is able to pass through.
• Translucent

  A type of object in which  only some of the light can pass through.
• Opaque


  A type of object in which none of the light can pass through.
• Specular reflection

  Light bounces off surfaces but stays parallel. Only possible on a smooth surface
• Diffuse Reflection

  Light bounces off surface but scatters in different directions. Reflects off rough surfaces.
• Uneven or rough surfaces reflect light rays in different directions. This scattering of light is called diffuse reflection.
•  smooth, shiny surfaces reflect light rays in a regular pattern. This allows us to see a clear image reflected back at us and is called regular reflection. Mirrors are a great example of this.
• The law of reflection 

  The way a light ray reflects off a surface follows a simple pattern. The incoming ray is called the incident ray. To work out the direction of the reflected ray, we can think of a line at right angles to the surface. This line is called the normal. As shown in the diagram below:

  • The angle between the incident ray and the normal is called the angle of incidence.
  • The angle between the reflected ray and the normal is called the angle of reflection.