Properties of Waves

• What should you be able to describe by the end of the video?

  How changes in atoms occur when electromagnetic radiation is generated or absorbed, and the hazards of ultraviolet, x-rays, and gamma-rays.
• What happens to atoms when electromagnetic waves are generated or absorbed?

  • Changes occur in atoms or nuclei
  • Electrons can move between energy levels
  • Gamma rays can be emitted from the nucleus of radioactive atoms
• How do lithium atoms emit electromagnetic waves when heated?

  Electrons move to higher energy levels and emit electromagnetic waves when they return to their original levels.
• What type of radiation can be emitted from the nucleus of radioactive atoms?

  Gamma rays
• What happens to the energy of a nucleus after emitting a gamma ray?

  • The nucleus has less energy than it had before emitting the gamma ray.
• What can happen when electromagnetic waves are absorbed by atoms?

  • Electrons can change energy levels.
• What is the frequency range of electromagnetic waves?

  From radio waves to gamma rays
• What are the hazards associated with ultraviolet waves, x-rays, and gamma rays?

  • Ultraviolet waves increase skin cancer risk and cause premature aging.
  • X-rays and gamma rays are ionizing radiation that can mutate genes and increase cancer risk.
• What is the effect of x-rays and gamma rays on atoms?

  They knock electrons off atoms when absorbed.
• How is the dose of radiation measured?

  In sieverts or millisieverts
• How can radio waves be produced?

  When electrons oscillate in an electrical circuit.
• What factors influence the damage caused by radiation?

  • Type of radiation
  • Dose of radiation
• What happens when radio waves are absorbed by an electrical circuit in an aerial?

  • They cause electrons in the circuit to oscillate.
  • This can create an alternating current with the same frequency as the radio waves.
• What are the key features of wave motion that should be described?

  Amplitude, wavelength, frequency, and period
• What is the definition of amplitude in wave motion?

  • Maximum displacement of a point on a wave from its undisturbed position
  • Represents how far the wave vibrates from the undisturbed position
• How is wavelength defined in wave motion?

  The distance from a point on one wave to the equivalent point on the adjacent wave
• What is the symbol used to represent wavelength?

  Greek letter lambda (λ)
• What is the definition of frequency in wave motion?

  The number of waves passing a point each second
• What is the unit of frequency?

  Hertz (Hz)
• How do you calculate the frequency of a wave from a diagram?

  Count the number of waves in one second
• What is the definition of period in wave motion?

  The time in seconds for one wave to pass a point
• How is the period of a wave calculated?

  • Period (seconds) = 1 / Frequency (Hertz)
• If a wave has a frequency of 100 Hertz, what is the period of the wave?

  0.01 seconds