Science, Electromagnetic Waves:

• Frequency (Hz) = number of waves passing through one point per second
• Electromagnetic (EM) waves - transverse waves. 
• What are EM waves vibrations? -Their vibrations or oscillations are changes in electrical and magnetic fields at right angles to the direction of wave travel.
• What can all EM waves do?

  1. transfer energy as radiation
  2. can travel through a vacuum such as in space
  3. travel at the same speed through a vacuum or the air
• What are the 7 different EM waves?

  
  

  1. Radio waves
  2. Microwaves
  3. Infrared
  4. Visible Light
  5. Ultraviolet
  6. X-rays
  7. Gamma rays
• What are the uses of Radio Waves?

  Radio waves are used for communication such as broadcasting television and radio, communications and satellite transmissions.
• What are Microwaves used for?

  Used for cooking food, communications and for satellite communications. Intense sources of microwaves can be dangerous through internal heating of body cells.
• What is Infrared light used for?

  Used by electrical heaters, cookers for cooking food, short-range communications like remote controls, optical fibres, security systems and thermal imaging cameras which detect people in the dark.
• What is Visible Light used for?

  Visible light is the light we can see, so is used in photography and illumination. It is also used in fibre optic communications, where coded pulses of light travel through glass fibres from a source to a receiver.
• What is UV used for?

  -Sterilisation, Water purification/disinfection, Medicine, Lighting, Killing bacteria.
• What are X-rays used for?

  
  

  -Can kill cancer cells. Directing an X-ray beam onto skin cancer cells, or cancer cells inside the body, can help to cure cancer. X-rays can also be used to produce images of the internal structure of the body, helping doctors to determine whether bones are broken or fractured.
• What are Gamma Rays used for?

  • Medical imaging and diagnostics, such as tracers
  • Cancer treatment (radiotherapy), by killing cancerous cells
  • Sterilization and disinfection of medical equipment and food
• What are the EM Waves with a short Wavelength?

  Gamma rays

  X-rays

  Ultraviolet
• What EM Waves have a long wavelength?

  -Radio waves, microwaves, infrared and visible light.
• What is the amplitude of a wave?

  • is its maximum disturbance from its undisturbed position.

  
• How are Radio Waves produced?

  - produced by oscillations in electrical circuits. When radio waves are absorbed by a conductor, they create an alternating current. This electrical current has the same frequency as the radio waves.
• What are health hazards of Infrared Rays?

   - can cause burns to the skin.
• What is useful about Infrared Waves have frequencies which are absorbed by some chemical bonds?

  -The internal energy of the bonds increases when they absorb infrared light, which causes heating. This makes infrared light useful for electrical heaters and for cooking food. All objects emit infrared light. The human eye cannot see this light, but infrared cameras can detect it. This ‘thermal imaging’ is useful for detecting people in the dark.
• What does Microwaves having frequencies which are easily absorbed by molecules in food make them useful?

  -The internal energy of the molecules increases when they absorb microwaves, which causes heating. So they can be used for heating liquids and food.
• What is Visible Light used for?

  -Used in photography and illumination. It is also used in fibre optic communications, where coded pulses of light travel through glass fibres from a source to a receiver.