What is a wave?

  • A wave is a means of transferring energy through a medium, without any net movement of that medium.
    • Transverse wave: A wave where the direction of vibration is perpendicular to the direction in which the wave travels. e.g. light, waves on a rope, water waves.
    • Longitudinal wave: A wave where the direction of vibration is para;;e; to the direction in which the wave travels. e.g sound, compression waves on a spring.

Key Terms

  • Frequency: The frequency (f) is the number of cycles completed at any one point per second.
  • Period: A period of a wave (T) is the time taken to undergo one complete cycle.
  • Diffraction: Diffraction is the ability of a wave to recover after meeting an obstacle.

Interference

  • Interference occurs when two waves meet. When this happens, the total displacement will be equal to the algebraic sum of the individual displacements. (All types of waves will undergo interference).
    • Constructive interference occurs when waves from two sources meet and the amplitude of the resulting wave is greater than the amplitudes of each of the individual waves.
    • Destructive interference occurs when waves from two sources meet and the amplitude of the resulting wave is less than the amplitude of each individual waves
  • Coherent waves: two waves that have the same frequency and wavelength.
  • Interference pattern: When waves from two or more coherent sources meet, the resulting wave pattern formed is called an interference pattern.

Stationary (standing) waves

  • stationary wave or a standing wave is produced when two waves of the same frequency and amplitude meet, moving in opposite directions.

The Doppler effect

  • The Doppler effect is the apparent change in the frequency of the waves due to the motion of the source of the wave or an observer.

 

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