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.

Bilder und Dateien der Mindmap