P6

Waves

When waves travel through a medium, they transfer energy (Not matter)

Frequency - Number of complete waves passing a certain point each second

Period - Amount of time it takes for a complete wave to pass a point

Wavelength - Length of a full cycle of a wave

Amplitude - Maximum displacement of a point on a wave from its rest position

Transverse Waves

Oscillation perpendicular to a direction of energy transfer

  1. Ripples in water
  2. Electromagnetic waves
  3. Waves on a string

Longitudinal Waves

Oscillations parallel to direction of energy transfer

Sound waves are longitudinal

Refraction

Wave Speed - Speed at which a waves transfers energy or the speed it moves at

Refraction - when a waves changes direction as it crosses a boundary between two materials at an angle to the normal

Slows down -> Wavelength decreases -> bends towards normal

Speeds up -> Wavelength increases -> Bends away from normal

EM SPECTRUM

Uses of EM Waves

  • Radio Waves - TV, Radio
  • Microwave - Satellite coms, Cooking
  • Infrared - Electric heaters, Cooking, Infrared cameras
  • Visible Light - Coms through optic fibres
  • UV Waves - Energy efficient lights, Sun tan beds
  • X-Rays - Medical imaging, medical treatments.

Dangers of EM Waves

Radiation Dose - Measure of the risk of harm to body tissues due to the exposure to radiation. It is measures in sieverts.

UV - Can prematurely age skin + Increase the risk of skin cancer

X-Rays - Gene mutation + Cancer