Waves

• Difference between longitudinal and transverse waves

  Transverse waves causes the medium to move, perpendicular to the direction of the wave & longitudinal waves caused the medium to move, parallel to the direction of the waves
• The amplitude of a wave is the maximum displacement of a point on a wave away from its understood position
• The wavelength of a wave is the distance from a point of one wave to the equivalent point to another wave
• The frequency is the amount of waves that passes a point each second
• The way speed is the speed of which the energy is transferred through the medium
• Wave speed = frequency x wavelength
• The period is the time in seconds for a wave to pass a point
• The speed of a sound wave in air can be measured by timing, how long it takes from the sound wave to travel a known distance through the medium
• to measure the speed of ripples of water surface, calculate the wave speed
• Electromagnetic waves are transverse waves, they transfer energy from the source of the waves to an absorber
• Example that illustrate, the transfer of energy by electromagnetic waves

  Transfer energy from the source (oven) to the absorber (food)
• Different substances may absorb transmit or reflect electromagnetic waves in the ways that vary with wavelength
• Some effects, for example, refraction are due to the difference in velocity of ways in different substances
• When electromagnetic waves are generated or absorbed changes take place in atoms or the nuclei of atoms
• Hazards to the body by ultraviolet waves

  • Could cause skin cancer
  • Skin to age, prematurely
• X rays & gamma rays

  • are ionising radiation.com cause the mutation of genes and cancer
• Radio waves - are used to transmit tv & radio signals & radio waves are used as they can travel long distance also has a longer wavelength and can spread out
• Microwaves - used for cooking & most food contain water molecules in which water molecules absorb the energy of microwaves, causing the food to increase in heat
• Infrared - used by electrical heaters, this is because the energy of infrared is easily absorbed by the surface of objects.
• Visible light - is fibre optic communication, that can carry large amounts of data over long distances with very little losed
• Ultraviolent – use the lightbulbs, ultraviolence light is absorbed by the internal surface of the bulb, and it is conved to visible light
• X-rays & gamma rays - are use for medical imaging both x-rays and gums are penetrative & so can easily pass through the body tissue