WAVES

WAVES

1. Parts of A Wave

   • Amplitude: Maximum displacement of a point of a wave from its rest position
   • Wavelength: Distance covered by 1 full cycle of the wave
   • Peak: Highest point above rest position
   • Trough: Lowest point below rest position
   • Frequency: Number of waves passing a point each second
   • Rest Position: Undisturbed position of particles when they are not vibrating
   • Time Period: Time taken for 1 full cycle of the wave

2. Mechanical Waves

   • Requires a medium to travel through
   • Causes vibrations of particles in solids, liquids and gases

3. Transverse Waves

   • Vibrations are perpendicular to the direction of travel
   • Peaks and Troughs
   • Energy is transferred from left to right. Particles move up and down

4. Can be described as Oscillations around a midpoint

5. All waves transfer energy not matter

6. Electromagnetic Waves

   • Causes oscillations in Electrical and Magnetic fields
   • Transverse waves
   • Transfer energy as radiation
   • Can travel through a vacuum
   • 300 million m/s
   • Continuous spectrum of waves

7. Longitudinal Waves

   • Vibrations are parallel to the direction of travel
   • Shows areas of compression and rarefaction
   • Wave transmitted through a medium

8. Wave Period and Wave Speed

   • Time Period = 1/Frequency
   • Wave Speed = Frequency X Wavelength

9. Sound Waves

   • Speed of Sound = Speed = Distance/Time
   • Speed of sound in air = 330 m/s
   • Ultrasound
     • Higher frequency than human hearing
     • 20,000 Hz
     • Breaks Kidney Stones/ Cleans Jewellery
     • Creates images of things not seen directly
     • Boundaries to create images
   • Sound is caused by the vibrations of particles
   • Longitudinal Waves
   • Can pass through Solids, Liquids and Gases
   • Cannot travel through a vacuum
   • The Ear
     • Sound waves enter the ear canal
     • Ear drum vibrates
     • 3 small bones transmit vibrations to the Cochlea
     • Electrical Signals sent to the Brain
     • Electrical Signals interpreted as sound
   • Properties of Sound
     • Frequency
       • Relates to the pitch
       • High Frequency = High Pitch
       • Low Frequency = Low Pitch
     • Amplitude
       • Volume of the Sound
       • High Amplitude = Loud
       • Low Amplitude = Quiet
   • Echosounding: Identifies objects such as distance in sea
   • Echolocation
     • Bats
     • Dolphins

10. Required Practicals

    • Ripple Tanks can be used to measure and calculate Frequency, Wavelength and wave speed on the surface of water
    • Using string to measure the speed of waves in a solid
    • Reflection of light by different types of surface
    • Refraction of light by different substances

11. Reflection and Refraction

    • Reflection
      • Waves reflected at a boundary
      • Angle of Incidence = Angle of Reflection
      • Specular Reflection
      • Echoes
      • Diffuse Reflection
    • Refraction
      • Change in direction of a wave at a boundary
      • Ray Diagrams
      • Density of a material can change a waves speed
      • Normal