waves

• waves are repeating movements that happen in the medium to transfer energy
• types of waves:

  1. medium
  2. direction of motion
• 1. medium

  • need medium to travel thru (mechanical) - eg: sound energy
  • don't need medium (electromagnetic) - eg: light energy, x-rays
• 2. direction of motion

  • perpendicular (transverse)
  • parallel (longitudinal)
• light is electromagnetic and transverse
• sound is mechanical and longitudinal
• frequency and time are inversely proportional
• speed of the wave = frequency x wavelength
• behavior of waves:

  1. reflected
  2. refracted
  3. diffracted
• reflection is the change in direction of the wave when it hits an obstacle
• law of reflection: angle of incidence = angle of reflection
• refraction is the change in speed of the wave when it changes mediums
• when speed in medium is less the medium is more dense

  when speed in medium is more the medium is less dense
• diffraction is the spreading of the wave as it goes thru a gap or around the corner
• if the gap is more than the wavelength the wave will move in a straight line
• if the gap is less than the wavelength the wave will move in curves
• 1: amplitude is how high the crest is & how deep the trough is

  2: wavelength is the distance between 2 successive crests or troughs

  3: time period is the time taken to complete one full cycle

  4: frequency is the number of cycles per second
• cases of refraction:

  1. when angle of incidence = 0 --> i = 0, r = 0
  2. when ray moves from less to more dense, i>r
  3. when ray moves from more to less dense, i<r