Electromagnetic Waves

Electromagnetic Waves

1. Micro Waves

   • Uses: cooking, mobile phones, communications and satellite transmissions (radar)
   • Produced by oscillating electrons in metals
   • Strongly absorbed by water
   • They make molecules of water vibrate which leads to heat
   • Microwaves start heating internally
   • Produced and received by aerials

2. Infra Red

   • Uses: heating, grills, toasters, remote controls, cable TV, heat treatment and security systems
   • Heat is caused by vibrating atoms and molecules
   • Given out by all objects that have a temperature
   • Can be detected by skin, thermal cameras and thermometers
   • Starts heating from the surface
   • Dark objects emit and absorb more infra-red than white objects

3. Visible Light

   • Uses: to see, for illumination in torches or lightbulbs, photography and lasers
   • Produced by atoms when electrons change energy levels
   • When an atom absorbs light, an electron moves to a higher energy level
   • The more levels they jump the higher the frequency

4. Ultra Violet

   • Uses: security markers, fluorescent lamps, washing powder, sunbeds and for disinfecting water
   • Produced when electrons change energy levels
   • You can absorb UV but get visible light (fluorescence)
   • Can ionise atoms and molecules
   • Damages skin and eye cells
   • Makes you blind or gives you skin cancer in large doses
   • Small doses are good

5. X Rays

   • Source: x-ray tubes
   • Can be detected by photographic film
   • Uses: observing internal structure, people, metal structure, airport security and archeology
   • Absorbed by bone but transmits or passes through air, skin or soft tissue
   • CT scans are more dangerous because they come in a higher dosage
   • Produced by accelerating electrons
   • Can cause ionisation and kill or damage our cells
   • Alters and damages our DNA cells which causes mutation

6. Gamma Rays

   • Source: radioactive substances like uranium
   • Made when there is a change in the nucleus of the radioactive substance
   • Detected by Geiger-muller tube
   • Uses; getting rid of bacteria, sterilise surgical equipment, detect and treat cancer
   • Used in radiotherapy
   • Partially absorbed by thick lead and concrete
   • Detected by photographic film
   • Dangerous because it kills and/or mutates cells

7. Radio Waves

   • Used: TV, Radio, Communications, Bluetooth, Satellite transmissions (radar)
   • produced by oscillating electrons in metals
   • Causes electrons in metals to oscillate, making an electrical current or voltage
   • Atoms, electrons or molecules vibrating leads to heat
   • Causes metals to heat up