Waves

Waves

1. Electromagnetic radiations

   • Travel as waves
     • Cover a continuous range of wavelengths called the electromagnetic spectrum
   • Move energy from one place to another
   • Can travel through a vacuum
     • Travel at the same speed
   • Sound waves and some mechanical waves are longitudinal and cannot travel through vacuum

2. Waves

   • Waves transfer energy
   • Waves may be either transverse or longitudinal
     • Electromagnetic waves are transverse
     • Sound waves are longitudinal
       • Longitudinal waves show areas of compression and rarefaction
     • Mechanical waves may be either transverse or longitudinal
     • Meaning or transverse, longitudinal and mechanical
       • Transverse waves vibrate at right angles to the direction of energy transfer of the waves
         • All electromagnetic waves are transverse waves
       • Longitudinal waves vibrate parallel to the direction of energy transfer of the waves
       • Mechanical waves need a medium to travel through
   • Electromagnetic waves
     • All types of electromagnetic waves travel at the same speed through a vacuum
     • Form continuous spectrum
   • Can be reflected, refracted and diffracted
     • Refraction
       • Waves undergo a change in direction when refracted off an interface

3. Frequency, wavelength and amplitude

   • Frequency
     • Is the number of waves passing a fixed point every second
   • Wavelength
     • The distance from one wave crest to the next
   • Amplitude
     • The height of the wave crest of the depth of the trough from the middle
     • The bigger the amplitude of the waves
   • All waves obey this rule
     • v = f x λ
       • v= speed in m/s2
       • f = frequency in Hz
       • λ = wavelength in m

4. Electromagnetic spectrum

   • Radiowaves
     • Television and radio
   • Microwaves
     • Used in mobile phones and satellite television
   • Infrared red
     • Used remote controls
   • Visible light
     • Photography
   • Ultraviolet
   • X-rays and Gamma radiation