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Physics review: Waves - Coggle Diagram

- - - - Image is laterally inverted
      - Same size as objects
      - virtual
      - same distance behind the mirror as the object
    - - i = r: the angle of incidence is always equal to the angle of reflection
      - The incident ray and the reflected ray lie on the same plane
  - - - Refraction: the bending of light when it passes through a medium to another
      - Angle of refraction: angle between refracted ray and the normal to the surface where it passes from one medium to another
    - - Rarer --> denser medium: towards the normal (because light speed decreases)
      - Denser --> rarer medium: away from the normal (because light speed increases)
      - Directly above the normal: light travels as a straight line
    - - n = sin i/ sin r = speed of light in rarer medium/ speed of light in denser medium
  - - - Total internal reflection: when a light ray strikes the inner surface of a material and 100% of the light reflects back inside it
        
        Conditions
        
        The light ray moves from a more dense medium to a less dense medium.
        
        The angle of incidence must be greater than the critical angle
      - Critical angle: the minimum angle of incidence at which total internal reflection can occur
    - - n = 1/sin c
    - - Optical fibre (communication
        
        Light travels by total internal reflection. It bounces along inside the fibre because each time its angle of incidence is greater than the critical angle --> no light is lost
      - Endoscope
        
        1 bundle carry light downs into the body
        
        1 bundle carries light back to the doctor
  - - - Principal axis: A line which passes through the centre of a lens
      - Principal focus/ focal point: The point at which rays of light travelling parallel to the principal axis intersect the principal axis and converge or the point at which diverging rays appear to proceed
      - Focal length: The distance between the centre of the lens and the principal focus
    - - Properties of images
        
        <f: virtual, upright, enlarged
        
        f --> 2f: inverted, real, enlarged
        
        2f: inverted, real, same size
        
        2f: inverted, real diminished
      - Used to correct long-sightedness
      - parallel light rays converge at the principal focus
    - - Properties of images
        
        always erect, diminished, virtual
      - Used to correct short-sightedness
      - Parallel light rays diverge from the principal focus
- - - - Compression: a region in a longitudinal wave where particles are close to each other
      - Rarefaction: a region in a longitudinal wave where particles are far away from each other
  - - - Solid (5000m/s in steel)>liquid (1500 m/s in water)>gas (340 m/s in air)
      - speed = distance/time
    - - Higher frequency (Hz) --> higher pitch
    - - Higher amplitude --> higher volume (dB)
- - - - communication
    - - heating food
      - communication
      - hazard: causes heating of organs
    - - cooking
      - remote control
      - security camera
    - - seeing, camera, telescope, microscope
    - - detecting fake notes
      - hazard: skin cancer, damaging eye cells
    - - scanning bones
    - - killing cells
      - treating cancer
      - hazard: killing living cells
  - - - Satellites
      - Mobile phones
      - Wireless internet
    - - It has longer wavelengths --> penetrate walls
      - Easy to diffract
    - - Analogue signals: a signal which varies continuously in frequency and amplitude
      - Digital signal: a signal that consists of a series of pulses which are either on or off
    - - bluetooth
      - terrestrial TV
      - radio stations
- - - - Trough: Minimum point of wave
      - Crest: Maximum point of wave
      - Wavelength: distance between 2 adjacent troughs or crests of a wave
      - Period: the time it takes for a wave to complete 1 oscillation
      - Frequency: number of wave each second
      - T = 1/f (period = 1/frequency)
    - - Longitudinal: direction of oscillations // direction of propagation
        
        Examples: sound, P (primary/ pressure waves)
      - Transverse: direction of oscillations perpendicular to direction of propagation
        
        Example: light, other electromagnetic waves, S (seismic waves)
    - - Wave: A process of energy transfer through oscillations, without matter being transferred with it
  - - - equal wavelengths
      - angle of incidence = angle of reflection
      - A wave hits a boundary between two media and does not pass through, but instead stays in the original medium
    - - In a deep medium
        
        Waves turn slightly away from the normal
        
        Increases speed, same frequency --> increases wavelength
        
        $defrac$
      - Happens when a wave passes a boundary between 2 transparent media and undergoes a change in speed
      - In a shallow medium
        
        Waves turn slightly towards the normal
        
        Decreases speed, same frequency --> decreases wavelength
    - - wave spreads out as it travels through a gap
      - shape: curve
      - most diffraction when length of gap = wavelength
      - $Single-Slit-Diffraction-1$