Waves

Waves

1. Waves transfer energy from one point to another, but they do not transfer matter

   • Longitudinal Waves
     • A wave in which the particles vibrate parallel to the direction in which the wave is travelling. Eg sound waves, slinky
   • Transverse Waves
     • A wave in which the particles vibrate at 90' to the direction in which the wave is travelling. Most waves in nature are transverse eg water waves, electromagnetic waves.

2. ·

   • the number of complete waves passing a fixed point in 1 second. Measured in Hertz (HZ)
     • Frequency
   • is the greatest displacement of the wave from its undisturbed position. measured in Metres
     • Amplitude
   • Wavelength-
     • Is the distances between two consecutive crests or troughs. given the symbol λ and is measured in Metres

3. The Wave equation

   • Speed of wave = frequency x wavelength
     • v = f x λ

4. Wave reflection

   • - The angle of incidence is always equal to the angle of reflection
     • - the wavelengths of the incident and reflected waves are equal
       • - there is continuity of the incident and reflected waves at the barrier
         • - the frequiences of the incident and reflected waves are equal - The speeds of the incident and reflected waves are equal
           • - the angle between a wave front and the direction of travel is always 90'

5. Wave refraction

   • ripple tank studies show that when waves travel from deep water into shallow water:
     • - the waves slow down
       • - the wavelength of the waves decrease
         • the frequency of the waves is unchanged

6. Sound waves

   • Sound waves are produced when an object vibrates at a frequency that the ear can detect. humans can hear from 20 Hz to 20 000 Hz
     • This decreases when hearing is damaged from
       • 1. too much ear wax
         • 2. Damage t the auditory nerve
           • 3. Illness or infections
             • 4. Old age
     • Ultrasound
       • Sound above 20 000 Hz cannot be heard by humans and is called ultra sound.
         • Sound travels through materials as a longitudinal wave as energy passes from molecule to molecule. The sound energy passes from particle to particle. that's why sound cant travel through vacuum where there is no particles.

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