Waves

• What is a transverse wave?


  A wave for which the oscillations are perpendicular to the direction of energy transfer
• What is a longitudinal wave?

  A wave for which the oscillations are parallel to the direction of energy transfer
• Examples of transverse waves:

  Electromagnetic waces

  Seismic s-waves
• Examples of longitudinal waves:

  Sound waves

  Seismic p-waves
• What are the 2 parts of a longitudinal wave called?

  Compressions and rarefactions
• What is a wave’s amplitude?

  The maximum displacement of a point in a wave from its undisturbed position
• What is wavelength?


  The distance from a point on a wave to the same point on the adjacent wave

  -> peak to peak or trough to trough
• What is the frequency of a wave?

  The number of waves that pass a given point each second
• What does a wave transfer?

  Energy
• How do sound waves travel through a solid?

  The particules in the solid vibrate and transfer kinetic energy through the material
• What are ultrasound waves?

  Waves which have a frequency higher than the upper limit of human hearing (20kHz)
• Uses of ultrasound waves:

  Medical imaging

  Shattering kidney stones
• State a difference between the mediums that

  P-waves and S-waves can travel through

  > P-waves travel through both solids and liquids

  > S-waves only travel through solids
• What technique is used to detect objects in deep water and measure water depth?

  > Echo sounding

  > High frequency sound waves are emitted, reflected and detected

  > Time difference between emission and detection alongside wave speed are used to calculate distances
• Order the types of electromagnetic radiation from lowest to highest frequency:

  Radio waves

  microwaves

  Infrared

  Visible light

  Ultraviolet

  X rays

  Gamma rays
• How do the speeds of EM radiation differ in a vacuum and in air?

  They all travel at the same speed in a vacuum and in air
• What property of waves in different mediums causes refraction?

  > Velocity

  > Wave speed is slower in denser materials, causing refraction
• In which direction (relative to normal) do waves refract when entering a denser medium?


  > They bend towards the normal

  > The angle of refraction is less than the angle of incidence
• What type of waves can be produced by oscillations in an electrical circuit?

  Radio waves
• How can radio waves create an alternating current in a circuit?

  When radio waves are absorbed, they can induce oscillations in a circuit with the same frequency as the waves themselves
• Uses of infrared radiation:

  > Electrical heaters

  > Cooking food

  > Infrared cameras
• Uses of microwaves radiation:

  > Satellite communications

  > Cooking food
• Uses of radio waves:

  > Television transmission

  > Radio transmission
• What wave phenomenon is used by lenses to form an image?

  Refraction
• How does a convex lens form an Image?


  Parallel rays of light are refracted and brought together at a point known as the principle focus
• What is meant by the focal length of a lens?

  The distance from the lens to the principle focus
• What is the difference between the image produced by a convex and concave lens?

  > Convex lenses can produce real or virtual images

  > Concave lenses can only produce virtual images
• What is specular reflection?

  Reflection of light off a smooth surface in a single direction
• What is diffuse reflection?


  Reflection from a rough surface which causes scattering
• How does a red colour filter work?

  > A red filter absorbs all wavelengths of light other than those in the red range of the spectrum

  -> This means only red light passes through the filter
• What determines the colour of an opaque object?

  > Different objects reflect different wavelengths of light by different amounts

  > The wavelengths that are most strongly reflected determine the colour
• What happened to the wavelengths of light that aren‘t reflected by an opaque object?

  Any wavelengths that aren’t reflected are absorbed by the object
• What do all bodies (objects) emit and absorb?

  Infrared radiation
• What happens to the quantity of infrared radiation emitted by an object as temperature increases?

  The hotter the object, the more infrared radiation it will emit
• What is a perfect black body?


  An object that absorbs all of the radiation that is incident upon it
• How much radiation does a perfect black body reflect or transmit?


  None
• What can be said about the rates of emission and absorption for a body increasing in temp?

  The body is absorbing radiation faster than it is emitting it