Electromagnetic Waves

• Light travels at 300 million metres per second (m/s).

  
• Waves with a very short wavelength have high frequency and high energy

  
• Waves with a very long wavelength have low frequency and low energy.

  
• Visible Light are the only EM waves that can be seen with the naked eye.

  
• Radio Waves are used for communication.

  
• X-Rays are a type of ionising radiation as they can penetrate our body and reveal pictures of our bones.

  
• Microwaves cause Internal heating of body cells

  
• X-rays cannot penetrate through bones, because its too dense.

  
• Which two EM waves are used in cooking?

  Microwaves and Infrared

  
• Why are Ultrasound waves safer than X-rays for a baby?

  They have less energy and dont damage cells of baby.

  
• X-Rays kill cancer cells and shrink tumours.

  
• Ultraviolet waves cause skinburn, skin cancer and early ageing skin.

  
• All objects absorb and emit infrared radiation.
• Two uses of Microwaves?

  
  

  - Heating food

  - Communicating with satellite

  - Can pass through earth atmosphere
• Two uses of Radio waves?

  
  

  - Transmit radio signals

  - Can travel long distances.
• Two uses of Infrared Radiation

  
  

  - Used to cook food in ovens

  - Used in Infrared cameras (track heat loss)

  - Can be easily absorbed by objects.
• Two uses of Ultraviolet.

  
  

  - Energy efficient light bulbs

  - Less energy

  - sun tanning.
• Two uses of visible Light?

  
  

  - Communication with optic fibre

  - Short wavelengths.
• X-Rays are absorbed by bones.
• Both gamma rays and x-rays are penetrating.