Using Waves

Using Waves

1. The Electromagnetic Spectrum

   • All transfer energy
   • All are transverse waves
   • Travel at speed of light in vacuum
   • Can all be reflected, refracted, diffracted
   • Frequency increases, wavelength decreases down the spectrum

2. Radio waves

   • Sources - radio and TV transmitters
   • Detectors - radio and TV serials
   • Uses - communication, radio, TV, FM

3. Microwaves

   • Sources - microwave transmitters and ovens
   • Detectors - microwave receivers
   • Uses - mobile phone, satellite communication, cooking
   • Microwave oven cooks food faster because water molecules in foo absorb microwaves and become hot, cooking from both inside and outside
   • Microwave ovens have metal screen to keep them inside because can heat human body tissue

4. Infra-Red Radiation

   • Sources - hot objects
   • Detectors - skin, blackened thermometer, special photographic film
   • Uses - IR cookers, heaters, night vision, TV remote control
   • Too much exposure can cause skin burns

5. Visible Light

   • Sources - luminous objects
   • Detectors - eye, photographic film, LDRs
   • Uses - optical fibres, photography

6. Ultraviolet

   • Sources - UV lamps, Sun
   • Detectors - skin, photographic film, some fluorescent chemicals
   • Uses - fluorescent tubes, UV tanning lamps
   • Overexposure can lead to sunburn and blistering, skin cancer, blindness
   • Ozone absorbs large quantities of Sun's UV radiations but due to decreasing ozone in pollution, may lead to more skin cancers

7. X-Rays

   • Sources - X-ray tubes
   • Detectors - photographic film
   • Uses - X-radiography to observe internal structure of objects + human bodies
   • Overexposure can cause cancer

8. Gamma Rays

   • Sources - radioactive materials
   • Detectors - Geiger muller tube
   • Uses - sterilising equipment and food, radiotherapy
   • Can cause damage to living cells, can cure and cause cancer