The Big Bang

The Big Bang

1. Basics of Waves

   • Amplitude
     • Displacement from rest position to crest
   • Wavelength
     • The length of a full cycle of the wave
     • Crest to Crest
   • Transverse Waves
     • Vibrations are perpendicular (at 90°) to the direction of energy transfer of the wave
     • Light, Waves on Strings, Ripples
   • Longitudinal Waves
     • The vibrations are parallel to the direction of energy transfer of the wave
     • Sound waves, ultrasound, shock waves
     • Sound waves, Ultrasound, Shock waves
     • Sound Waves, Ultrasound, Shock Waves
   • Wave Speed = Frequency x Wavelength

2. Waves Properties

   • Reflection
     • What allows us to see objects
       • Light bounces off them into our eyes
     • Light travelling in the same direction from an...
       • ...even surface
         • Light is reflected at the same angle
           • Clear reflection
       • ...uneven surface
         • Light Reflects off at different angles
     • Angle of INCIDENCE=Angle of REFLECTION
     • RAY DIAGRAM

3. Diffraction

   • Waves spreading out when at the edges when they pass through a gap or pass an obstacle
   • The longer the wavelength, the more the wave spreads out

4. Refraction

   • When a waves crosses a boundary between two substances it changes direction
   • Waves are only refracted if they meet a new medium at an angle
   • If they're travelling along the normal they will change speed, but are NOT refracted

5. The EM Spectrum

   • Uses and Dangers of EM Waves
     • Microwaves
       • Uses=Satellites
       • Dangers=Burns, Cancer
     • Radio
       • Uses: TV, Radio
       • Dangers=None
     • Infra Red
       • Uses=Cooking, Night Vision
       • Dangers=Burns
     • Visible
       • Uses=Seeing
       • Dangers=Eye Damage
     • Ultra Violet
       • Uses=Discos, Tanning
       • Dangers=Skin Cancer
     • X-Ray
       • Uses=Medical Imagery, Security
       • Dangers=Cancer
     • Gamma
       • Uses=Observing the Universe
       • Dangers=Cancer
   • The Basics
     • EM Waves with different wavelengths have different properties
       • • All types of EM Waves travel at the same speed in a vaccum
         • EM Waves have higher frequencies and shorter wavelengths
         • Randy Men In Violet Underwear eXite Girls

6. Sound Waves

   • We hear sounds as vibrations
     • They're passed through the surrounding medium as a series of compressions
   • Sound travels faster in solids than liquids, and faster in liquids than gases
   • Sound can't travel in space because it's mostly a vaccum
   • Reflection and Refraction
     • Sound Waves can be reflected by hard flat surfaces
     • Echoes are Reflected Sound Waves
     • Sound waves will refract as they enter different media
       • As they enter denser material, they speed up
   • The higher the frequency, the higher the pitch

7. The Origin of the Universe

   • Expanding
     • Galaxies moving away from eachother
   • The Doppler Effect
   • Red-shift
     • The more distant the galaxy, the more red it appears
   • Big Bang Theory
     • All matter and energy in Universe was compressed into a small space
       • It exploded from that point and started to expand
     • 14 billion yrs ago
   • Cosmic Microwave Background Radiation
     • low frequency electromagnetic radiation coming from all parts of the universe
     • Universe still hot after Big Bang, high frequency radiation emitted
       • As universe expanded and cooled, radiation dropped infrequency, seen as microwave radiation

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