Properties of waves

• Amplitude


  The maximum displacement of a point on a wave away from its undisturbed position
• Transverse wave


  • Amplitude is the furthest point the wave vibrates from the undisturbed position
• Wavelength


  The distance from a point on one wave to the equivalent point on the adjacent wave
• Wavelength symbol


  Greek letter lambda (λ)
• Frequency


  The number of waves passing a point each second
• Frequency unit


  Hertz (Hz)
• Calculating frequency from a diagram


  Count the total number of waves in 1 second
• Period


  The time in seconds for one wave to pass a point
• Calculating period from frequency

  Period (s) = 1 / Frequency (Hz)
• Period = 1 / 100 Hz = 0.01 s
• Electromagnetic waves


  Waves generated or absorbed when changes take place in atoms or nuclei of atoms
• Generating electromagnetic waves from atoms

  1. Electrons move to higher energy level

  2. Electron returns to original energy level

  3. Electromagnetic wave (e.g. light) is generated
• Generating electromagnetic waves from atomic nuclei

  1. Gamma rays emitted from radioactive atoms

  2. New nucleus has less energy than before
• Electromagnetic waves can also be absorbed by atoms, causing changes like electrons changing energy levels
• Types of electromagnetic radiation

  • Radio waves
  • Ultraviolet waves
  • X-rays
  • Gamma rays
• Ultraviolet waves


  • Increase risk of skin cancer
  • Cause premature skin aging
• 1. rays and gamma rays

  • Ionizing radiation that knocks electrons off atoms
  • Can cause gene mutation and increased cancer risk
• Radiation dose


  Measured in sieverts or millisieverts
• Producing radio waves


  1. Electrons oscillate (move back and forth) in an electrical circuit

  2. Radio waves can be absorbed by an aerial, causing electrons in the circuit to oscillate and create an alternating current
• Absorbed dose


  The amount of radiation energy that is absorbed by a material or organism. It is measured in units of grays (Gy), where 1 Gy equals 1 Joule of radiation energy absorbed per kilogram of tissue.
• Equivalent dose


  A measure of the biological impact of radiation on living tissue. It takes into account the type of radiation, as well as the absorbed dose. Equivalent dose is measured in units of sieverts (Sv), where 1 Sv equals 1 Joule of radiation energy absorbed per kilogram of tissue.
• Low doses of radiation


  Generally not harmful to human health.
• Effective dose


  A measure of the overall risk of harm from radiation exposure. It takes into account the type and energy of the radiation, as well as the sensitivity of different organs and tissues to radiation. Effective dose is also measured in units of sieverts (Sv).
• Higher doses of radiation

  Can increase the risk of cancer and other health problems.
• ALARA


  An acronym for "as low as reasonably achievable." It is a principle for minimizing radiation exposure.