Waves Physics

• Frequency = 1/Time period
• Wavelength is the distance between two consecutive points on a wave that are in phase.
• Speed of sound = 340m/s/s
• Intensity is directly proportional to amplitude squared
• The speed of light is approximately 299,792,458 m/s
• Radio waves have the longest wavelength and lowest frequency
• Light travels at different speeds through different materials (refractive index)
• When light passes from one medium into another with a lower refractive index, it bends away from the normal line
• When light passes from one medium into another with a higher refractive index, it bends towards the normal line
• Electromagnetic radiation travels at the same speed regardless of its type or energy level
• Gamma rays have the shortest wavelength and highest frequency
• Wave

  A disturbance or oscillation that travels through space and time, usually with a periodic pattern
• Phase


  Position within an oscillation (e.g. peak or trough)
• Phase Difference


  The degree/extent to which two waves or two points on the same wave are through their oscillations i.e. how far through an oscillation each wave is, measured in radians/degrees
• Two points on a wave are in antiphase if they have a path difference of (n + 0.5) lamda, where n is a whole number
• Two points on a wave are in phase if they have a path difference of n lamda, where n is a whole number
• Transverse waves

  The Oscillation of particles is perpendicular to the direction of travel of the wave
• Longitudinal waves

  The Oscillation of particles is parallel to the direction of travel of the wave
• Progressive waves

  Transfer of energy as the result of oscillations of the medium through which the energy is travelling
• Mechanical waves

  Energy is transferred through a medium (i.e. by the oscillation of particles)
• Wave medium

  The material through which a wave travels (air, liquids, solids)
• Wave displacement

  The distance moved from equilibrium for a point on a wave
• Amplitude

  The maximum displacement from the equilibrium position
• Wavelength

  The minimum distance between two points oscillations in phase, for example between one peak to the next
• Wave Period

  The time taken for one complete wavelength to pass a given point / to complete one oscillation.
• Frequency

  The number of wavelength cycles passing a given point per unit time
• Phase

  The position of an oscillating particle or field at a given time on a wave cycle
• Wave speed

  The distance travelled by the wave per unit time
• Velocity = Frequency x Lamda
• Velocity = Lamda/Time
• Electromagentic waves

  C = F x lamda
• Reflection

  the change of direction of propagation of a wave when it meets a boundary
• Reflection occurs when …

  A wave changes direction at a boundary between two different media, and remains in the original media
• Refraction

   the change in direction of waves as they move between materials with different properties
• Refraction occurs when …

  A wave changes direction as it enters a new medium, due to a change in the speed of travel
• Diffraction

  the process by which wave energy spreads perpendicularly to the dominant direction of wave propagation. If the gap is increased, waves on the other side will spread out less.
• Only transverse waves can be polarised
• Intensity = Power/Area
• Amplitude squared is directly proportional to intensity
• If amplitude is doubled then intensity will increase by a factor of 4