P1A Topic 1

P1A Topic 1

1. Solar System

   • Geocentric Model
     • Ancient greeks
     • Everything orbited the earth in circles
   • Heilocentric model
     • Introduced Copernicus 1543
     • Condemned by the church
     • Galileos observation of Jupiter's moons
     • Sun
   • Current model
     • Ellipiticals

2. Waves

   • Properties
     • Amplitude (height of the wave)
     • Frequency (waves per second)
     • Wavelength (distance of one peak to the next)
     • Speed (How fast)
   • 2 types
     • Transverse (the vibrations are 90 degrees to the direction of travel)
     • Longitudinal (the vibrations are along the same direction of travel)
   • Waves transfer energy and information without transferring matter.

3. Reflection

   • Wave hits boundary between one medium and another.
   • The angle of reflection r is the same as the angle of incidence i
   • Occurs because of a change in density.
     • air to glass.

4. Refraction

   • EM waves travel slower in more dense.
   • Hits face on, no refraction, same direction.
   • Hits at a angle wave changes direction.
     • bending effect
     • Air to glass bends towards the normal
     • Glass to air bends away from the normal

5. Lenses

   • Converging lens (convex)
     • Causes rays to converge to a focus
   • Diverging lens (concave)
     • Causes rays to diverge
   • Focal point one at the front, one at the back.
   • Focal length
     • Distance from the lens to its focal point
   • A real image is there (projected on a screen) a virtual is not (can not be projected on a screen)

6. Telescopes

   • Refracting telescope
     • In a refracting telescope, the objective lens forms a image inside the tube. Eyepiece then magnify's it.
       • Objective lens = Convex lens
     • The rays are so far away they're pretty much parellel
   • Reflecting telescope
     • Uses two mirrors and a eyepiece lens.