Light and Optics

• Natural light is produced by hot objects like the sun or incandescent light bulbs.
• Properties of light - light travels in straight lines, light can be reflected, light can be refracted, light is a form of energy
• optical device - any device that uses light - lenses, mirrors, prisms
• • microscope - optical device used for viewing very small things
• microscope - has at least 2 lenses: objective lens, eyepiece lens
• microscope - when light shines through a very thin specimen, a large image is produced that you can see by looking through the eyepiece
• telescope - optical device used for viewing distant objects
• telescopes provide enlarged images of distant images by using lenses and mirrors, or a combination of both to collect light from distant objects and bring it to your eyes
• 2 types of telescopes: reflecting telescope, refracting telescope
• refracting telescope - uses 2 lenses to form an enlarged image
• refracting telescope - the larger lens is the objective lens that gathers light and focuses rays towards the eyepiece
• reflecting telescope - uses mirrors and a lens to form an enlarged image
• reflecting telescope - one of the mirrors is a large circular mirror that curves inward which gathers light very well
• binoculars - device used to view distant objects
• binoculars - made up of 2 short refracting telecsopes fitted together and has reflective prisms inside
• depending on the situation, light can: reflect, transmit or both
• glare - light relfected from glass or other shiny surfaces
• ray diagrams - diagrams used to show how light travels
• each ray has an arrow to show the direction it's travelling in
• light rays travel away from the source in every direction
• ray diagrams can help explain the intensity/brightness of a light changes with further distance
• the further you are from a light source, the fewer number of \light rays will reach your eyes
• shadow - if an object is between a light source and our eyes, it is perceived as a lack of light
• transparent material - allows light to pass through it with little to no reflection, no shadow is created
• transluscent material - material that allows some light through but not all, creates a shadow
• opaque material - material that lets NO light through, like a blackboard or a brick wall, a shadow is created behind these objects when light is shone on them
• luminous - object that produces light: candle, fire etc.
• non luminous - object that doesn't produce light but may reflect it,

  • We see non-luminous objects because light from another source is reflected off of it
• • regular reflection - reflection occurs when parallel rays hit a smooth surface
  • all rays reflect at the same angle
• diffuse reflection - refelction happens when rays come in parallel to each other but then hit a rough surface

  all rays relfect at different angles, rays do