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P5 (Waves (Properties (amplitude - distance from crest/trough to middle,…

- - - - Flashing light (strobe) to find wavelength
      - Number of rotations of motor per second for frequency
    - - Time how long it takes to hear on echo
      - Pair of microphones certain distance apart
      - Connect to oscilloscope
      - Waves show time for sound to travel between microphones
      - Can use for sound in liquid or solid
- - - - Forgery detection
      - Kills bacteria in water
      - Makes bodily fluids glow
    - - Kill cancer cells
      - Kill bacteria on food
    - - Satellites, WiFi & Bluetooth
      - Heat water/fat in microwave ovens
    - - UV can damage DNA of skin cells, causing cancer
      - UV can cause cataracts (cloudy corneas)
      - X-rays also cause cancer
      - Gamma rays damage/kill body cells
  - - - Thermal imaging camera produces a thermogram
      - Shows regions of different temperatures
      - Pixels inside a charge-coupled device (CCD) absorb infrared to produce image
      - Can also show problems with blood flow
    - - Bones absorb X-rays, but soft tissues do not
      - Photographic film darkens when it absorbs X-rays
      - Computerised tomography (CT) scans uses X-rays
      - A CCD also detects X-rays, shows differences in intensity
    - - Used as tracers (radioactive substance that emits rays)
      - Patient is injected, organs (e.g. kidney) absorb the tracer, produce image
      - Used to find leaks in underground pipe (more rays above leak)
- - - - Sound moves away from normal
      - Wavelength increases
      - (Frequency remains the same)
    - - Reflected (echo)
      - Transmitted (and possibly refracted)
      - Absorbed
      - Depends on densities
      - If densities are very different, more sound is reflected
  - - - Waves reflect from different boundaries in the body
      - Machine calculates distances using time & velocity
      - Baby imaging, kindey stones, blood flow
      - Echo-sounding & sonar used to find water depth
  - - - Pinna
      - Auditory canal
    - - Ear drum
      - Ossicles
        
        Hammer
        
        Anvil
        
        Stirrup
      - Oval window
    - - Semicircular canals
      - Cochlea (contains fluid)
      - Auditory nerve
- - - - Brings waves to a point (principal focus)
      - Corrects long-sightedness by refracting light inward
    - - Spreads waves out, as if they came from a point (virtual focus)
      - Corrects short-sightedness by refracting light outward
    - - Magnifying glass (convex, virtual, magnified, upright)
      - Camera (convex, real, diminished, inverted)
      - Spy holes (concave, virtual, diminished, upright)
    - - Ray from top of object to lens, parallel, then through focal point
      - Ray from top of object through center
      - Where they cross, or appear to come from, is top of image
  - - - Prism splits white light into spectrum
      - Each frequency travels at different speed in glass
      - Each frequency is refracted by different amount
      - Higher frequencies refracted more
    - - Filters absorb frequencies of light, but transmit others
      - E.g. red filter aborbs everything but red frequencies
      - No light gets through red & green filter together
    - - Mirror reflection is specular, or regular
      - Paper doesn't reflect because scattering is diffuse
      - Milk is white because it scatters all wavelengths
      - Molecules is atmosphere scatter blue frequencies