P5 - Light and the Electromagnetic Spectrum

• EM waves are transverse waves
• Electromagnetic waves transfer energy from source to observer
• in a vaccum electromagnetic waves travel at the same speed
• Radio waves, micro waves, infrared, visible, ultraviolet, X-rays, gamma rays
• Visible light is made up of red, orange, yellow, green, blue, indigo and violet
• Which part of the electromagnetic spectrum has the longest wavelength?

  radiowaves
• Which part of the electromagnetic spectrum has the shortest wavelength?

  gamma waves
• Which part of the electromagnetic spectrum has the lowest frequency?

  radiowaves
• Which part of the electromagnetic spectrum has the highest frequency?

  gamma waves
• How does the frequency of an electromagnetic wave affect the potential danger associated with it?

  The potential danger increases as the frequency increases
• harmful affects on microwaves:internal heating of body cells
• harmful effect of infrared:skin burns
• harmful affect of UV:Damage to surface cells and eyes, skin cancer and eye conditions
• harmful effect of x-rays and gamma rays:Mutation or damage to cells in the body
• uses of radio waves:Broadcasting, communications and satellite transmissions
• uses of microwaves:Cooking, communications and satellite transmissions
• uses of infrared:Cooking, thermal imaging, short range communications, optical fibres, TV remotes, security systems
• uses of visible light:Vision, photography and illumination
• uses of ultraviolet:Security marking, fluorescent lamps, detecting forged bank notes, disinfecting water
•  uses of x-rays:Observing the internal structure of objects, airport security scanners, medical x-rays
• uses of gamma rays:Sterilising food and medical equipment, detection of cancer and its treatment
• How can radio waves be produced

  oscillations in electrical circuits
• what can radio waves induce

  oscillations in electrical circuit
• What can changes in atoms and nuclei do? (2 things)

  generate radiations over a wide frequency range, be caused by absorption of a range of radiations
• When waves are refracted what two properties are changed?

  Direction and speed
• When a wave slows down, which way does it refract?

  Towards the normal
• When a wave speeds up, which way does it refract?

  away from normal
• What can affect how much a wave is refracted?

  wavelength
• How does wavelength affect the amount of refraction?

  
  

  Short wavelengths are refracted more
• What two things are always true in reflection?

  angle of incidence=angle of reflection
• What can changes in atoms and nuclei be caused by?

  Absorption of a range of radiations
• How are gamma rays produced?

  In the nucleus from radioactive decay to stabilise the nucleus.
• How are X-rays produced?

  They are emitted when electrons return to a lower energy level and emit high energy radiation
• materials interact with EM waves differently depending on the wavelength
• Black is a better emitter of radiation
• When light splits into the colours of the spectrum

  colours have different wavelengths = travel at different speeds = so refract at different amounts