Light and the electromagnetic spectrum P5

• What type of waves can be produced by oscillations in an electrical circuit?

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

  They induce oscillations at the same frequency
• Where do gamma rays originate from?

  Changes in the nuclei of atoms
• What health effects can ultraviolet waves cause?

  Skin aging and increased skin cancer risk
• What health effects can X-rays and gamma rays cause?

  They can cause mutations and increase cancer risk
• What health effects can infrared rays cause?

  Infrared waves can cause burns to skin
• How does electromagnetic radiation affect electron arrangement in atoms?

  It can change electron arrangement by absorption
• How do atoms become ions?

  By losing an outer electron
• What are the effects of body cells absorbing radiation?

  Large amounts damage cells; smaller amounts mutate
• What is a use of radio waves?

  Communications over long distances
• What is a use of microwaves?

  Cooking food by heating fat and water
• What are uses of infrared radiation?

  Cooking, infrared cameras, short-range communication
• What are uses of visible radiation?

  Illuminating and fiber optics for communication
• What are uses of UV radiation?

  Sterilization, energy-efficient lamps, sun tanning
• What are uses of X-rays?

  Medical imaging and treatment
• What are uses of gamma rays?

  Medical treatments like radiotherapy for cancer
• Which waves of the EM spectrum are regarded as most dangerous?

  Gamma and X-rays
• Why are gamma and X-rays considered the most dangerous?

  They have the highest energy
• What do all bodies emit and absorb?

  Infrared radiation
• How does the quantity of infrared radiation emitted by an object change with temperature?

  The hotter the object, the more infrared radiation it emits
• What happens to the type of radiation emitted by an object as temperature increases?

  The hotter the body, the shorter the wavelength of radiation
• What is required for a body to be at a constant temperature?

  Emit radiation at the same rate it absorbs
• What factors affect the intensity and wavelength distribution of any emission?

  • Intensity and wavelength distribution depend on temperature
• What is meant by intensity in the context of radiation?

  Power transferred per unit area
• What happens if the average power that an object radiates is less than it absorbs?

  The temperature of the object will decrease
• What can be said about the rates of emission and absorption for a body increasing in temperature?

  The body absorbs radiation faster than it emits
• What are two factors that affect the temperature of the Earth?

  1. The Earth’s rate of absorption and emission of radiation
  2. The amount of reflection of radiation into space
• How does the Earth’s atmosphere affect radiation?

  The atmosphere absorbs or reflects radiation from the sun
• What happens to the radiation emitted from the Earth?

  It is absorbed and re-emitted by greenhouse gases
• What type of waves are electromagnetic waves?

  Transverse
• What do electromagnetic waves transfer?

  Energy (not matter)
• What type of spectrum do electromagnetic waves form?

  A continuous spectrum
• What is the order of the electromagnetic spectrum in increasing wavelength?

  • Gamma
  • X Ray
  • UV
  • Visible
  • Infrared
  • Microwaves
  • Radio
• What is the highest frequency electromagnetic wave?

  Gamma waves
• What is the highest energy electromagnetic wave?

  Gamma waves
• What properties are shared by all electromagnetic waves?

  • They are all transverse waves
  • They all travel at the same speed (3x10⁸ m/s)
  • They can travel through a vacuum
• What range of frequencies of electromagnetic waves can be detected by the human eye?

  400-700 nanometres
• How do the speeds of EM radiation differ in a vacuum and in air?

  They all travel at the same speed
• What can happen when radiation strikes an object?

  • It can be transmitted
  • It can be reflected
  • It can be absorbed
• What is total internal reflection?

  Light is completely reflected at a boundary