Waves

Waves

1. Two types of waves

   • Transverse
     • The vibrations are at 90 degrees to the way the wave travels
     • Example - water waves
   • Longitudinal
     • The vibrations travel along the direction in which the wave travels
     • Example - sound waves

2. Describing waves

   • Amplitude
     • It is the height of the wave (from rest to crest or rest to trough)
   • Wavelength
     • It is the distance from one peak to the next
   • Frequency
     • How many complete waves there are per second passing a certain point
     • Measured in Hertz
     • 1 Hz = wave peak per second
   • Time period
     • Is the time taken for a source to produce one wave
     • Time period= 1/frequency
     • 1 over F/T

3. Speed = Frequency X Wavelength

   • Speed = m/s
   • Frequency = Hz
   • Wavelength = m

4. Diffraction

   • Occurs when waves spread out after passing through a gap or round an obstacle
   • Maximum diffraction occurs when the gap is the same length as the wavelength

5. Electromagnetic waves

   • There are seven types
     • Radio waves
       • Radio's and television's both use radio waves
     • Microwaves
       • For cooking and satellite tv transmissions
       • Internal heating of body tissue
     • Infrared
       • To cook foods and by remote controls
       • Skin burns
     • Visible light
       • For sight, in photography, and in optical fibres
     • Ultra violet
       • In fluorescent lamps and security devices
       • Damage to surface cells and blindness
     • X-rays
       • To view the internal structure of objects and materials
       • To produce an x-ray image x-ray radiation is directed through the object or body onto a detector plate
         • The brighter bits are where fewer x-rays get through
     • Gamma rays
       • To sterilise medical instruments by killing all the microbes
       • Cancer and mutation
   • They are all transverse waves and travel at the same speed through a vacuum 300 000 000 m/s
   • They form a continuous spectrum
   • They all transfer energy
   • They can all be reflected, refracted and diffracted

6. Refraction

7. Reflection

8. Radiation

9. Satellite can travel through a vacuum

Bilder und Dateien der Mindmap