Waves

• What is amplitude?


  The distance from the equilibrium point to the top of the wave

  
• What is the wave length?


  Distance between the same points on adjacent waves

  
• What is frequency?


  The number of complete waves passing a certain point per second

  
• What is a period?


  The amount of time it takes for a full cycle to pass a certain point per second
• What is the equation linking frequency and periods?


  Period (s) = 1/f (Hz)
• Diagram of a transverse wave

  
• In transverse waves in what direction are the oscillations and vibrations travelling?


  Oscillations are perpendicular to the direction of energy transfer. Vibrations are side to side
• Examples of transverse waves


  - Electromagnetic waves

  - Ripples in water

  - A wave on a string
• In longitudinal waves in what direction are the oscillations and vibrations travelling?


  Oscillations are parallel to the direction of energy transfer. Vibrations are in the direction of the wave
• Examples of longitudinal waves


  - Sound waves

  - Shock waves
• What is the equation for wave speed?

  
• What piece of equipment is used to detect waves?

  Oscilloscope
• What is the required practical used to measure the speed of waves?


  A dipper or ripple tank

  
• What is the first stage in using a ripple tank?


  Dim lights and turn on the strobe light
• What is the second stage in using a ripple tank?

  Increase the frequency of the strobe light until the wave pattern on the screen appear's to freeze
• Why does it look like the screen has frozen?

  The frequency of the strobe light is equal to the frequency of the waves
• Why is using a ripple tank good formeasuring small wavelengths?


  The distance between each shadow is equal to one wavelength so it is quite accurate
• Required practical : investigates waves on springs
• What is the first step?

  Set up a signal generator, a vibration traducer, string, pulley and masses
• What is the second step?

  Adjust the frequency on the signal generator to change the length of the wave on the string. Keep doing this until you see a clear wave on a string. The frequency will be different due to different lengths of string.
• What is the third step?


  Measure the wavelength. To do this measure lengths of all half wavelengths then find the mean and double it to get the value of the full wavelength. The frequency is whatever you set the signal generator to.
• What three things can happen when a wave hits a boundary?

  1- The wave gets ABSORBED by the material, transferring energy to the materials energy stores

  2- Waves are transmitted, carry on in the material. This is called REFRACTION

  3- Waves are REFLECTED
• What is the rule for reflected waves?


  Angle of incidence = angle of reflection
• Ray diagram

  
• What is specular reflection?


  Waves are reflected in ONE DIRECTION by a SMOOTH surface
• What is diffuese relection?

  Waves are relected by a ROUGH surface in MANY DIRECTIONS
• What is refraction?


  When waves change direction between the boundaries of materials
• What affects how much a wave is refracted?


  Its speed and how dense the material is
• What is optical density of a material is a measure of...


  How quickly light can travel through. The higher yje optical density, the slower light waves travel through a material
• Ray diagram to show refraction

  
• Required practical : Investigating light

  1- Put a transparent rectangular block of material on the middle of a piece of paper

  2- Use a ray box to shine a ray light at the middle of the block, trace the incident ray and the emerging ray

  3- Join the two lines.

  4- Drawn the normal then measure the angle between the incident ray and the refracted ray.

  5- Repeat
• You can do the same practical with different densities and roughness objects


  You can do the same practical with different densities and roughness objects
• What type of waves are electromagnetic ones?


  Transverse waves that transfer energy from a source to an absorber
• Electromagnetic wave order


  Radio waves

  Microwaves

  Infrared

  Visible light

  Ultra violet

  X-ray

  Gamma rays
• What Mnemonic can you use to remember the spectrum


  Richard Married Ian's Very Ugly eX Girlfriend

  Running Men In Vests Usually eXcite Girls
• What happens to wavelengths as you go down the EM spectrum?


  It decreases
• What happens to frequency as you go down the EM spectrum?


  It increases
• What are EM waves made of?


  Oscillating electric and magnetic fields qith an a.c current
• Uses of radio waves


  - Radio signals

  - TV and radio transmissions
• Uses of microwaves

  - Satellites

  - Microwaves