P4 - Waves

P4 - Waves

1. Light

   • Laws of Reflection
     • Angle of incidence is equal to angle of reflection Normal, incidence and reflected ray all lie on the same plane
     • Reflection in A Plane Mirror
       • Characteristics -  1.Virtual 2. Same size 3. Same distance from mirror 4. Upright 5. Laterally inverted - right on mirror is left irl
     • Total Internal Reflection
       • Critical Angle - angle of incidence where angle of reflection is 90 when light travels from more to less dense materials Total Internal Reflection - When angle of incidence is bigger than critical angle, rays are totally reflected back into medium, light travels from more dense to less dense medium
   • Laws of Refraction
     • Speeds up - moves away from normal Slows down - moves towards normal Only occurs when light moves through a different medium
     • Parallel Sided Glass Block
     • Apparent and Actual Depth
   • Optical Nerve
     • Light bounces off more dense layer to less dense layer - angle of refraction is greater than critical angle, resulting in total internal reflection Uses - transfer information at a faster rate and prevent any loss of information, endoscopy
   • Dispersion of Light
     • When white light goes through a prism and the differing speed and change in medium causes it to split into it's individual colours (ROYGBIV) Red light - Longest wavelength and fastest speed, and it is diffracted first Violet light - shortest wavelength and slowest speed, therefore refracted the most Frequency stays the same, as it is dependant on source
   • EM Spectrum
     • Uses of Different Waves
       • Radio - radio signals Microwave - heating of water, satellite communication Infrared - heating effect, remote controls Visible Ultraviolet Xray - medicine, security Gamma - measuring thickness, cancer treatment
     • Changes Between Waves
       • Frequency increases as you go down Wavelength decreases
     • Properties of Electromagnetic Waves
       • Same : -transverse waves -travel at the same speed -all can travel through vacuum -all have electrical and magnetic components Difference - wavelength and frequency

2. Lens

   • Converging lens - convex
   • Virtual Images
     • Images that can't be projected onto a screen Identified by having image and object on same side of lens or if object distance is less than or equal to focal length 
   • Important Parts
     • Optical center - center of lens Focal length - distance from lens to focal point Focal point - point where light rays converge Principal axis - midpoint line that passes through optical center
   • Real Image
     • Image that can be projected onto a screen Identified if image is on opposite side of object If object distance is double focal length - same size but inverted

3. Types of Waves

   • Transverse
     • Distance between crest and crest - wavelength Amplitude - distance between mean position and and top of crest Frequency - no of waves passing in a time frame (waves per second = Hertz)
   • Longitudinal
     • Movement of sound  Rarefraction - areas of low pressure and particles are far apart Compression - areas of high pressure and particles are close together
     • Reflection of Sound
       • Hits and is reflected off plane barrier, Reflection is always perpendicular to incoming ray/wave
     • Refraction of Sound in Deep and Shallow Water
       • Shallow water - shorter wavelength and slower Longer water - longer wavelength and fastera
   • Wavefront
     • Imaginary line joining all crests of  a wve