Em spectrum

• What does the e/m spectrum stand for?

  Electromagnetic spectrum
• What is the range of the electromagnetic spectrum?

  From very long wavelengths to very short wavelengths
• What is the order of the electromagnetic spectrum starting from the longest wavelength?

  Radio waves, microwaves, infrared, visible light, UV, x-rays, gamma rays
• How does wavelength relate to frequency and energy in the electromagnetic spectrum?

  Decreasing wavelength means increasing frequency and energy
• What are the three types of radiation known as ionizing radiation?

  UV, x-rays, gamma rays
• What is ionizing radiation?

  Radiation that can knock electrons out of atoms
• Why is ionizing radiation considered more dangerous?

  It can cause DNA damage leading to cancer
• What is a common risk associated with UV radiation?

  Skin cancer and sunburn
• What can infrared radiation cause?

  Skin burns and heating of tissues
• How do microwaves affect internal cells?

  They can heat up internal cells
• How are radio waves produced?

  By oscillating electrical currents
• What produces visible light?

  Electrons dropping to lower energy levels
• What is a common use of gamma rays?

  Curing cancer through radiotherapy
• What is the speed of all electromagnetic waves in a vacuum?

  $3 \times 10^8 \text{ m/s}$
• How does the Earth's atmosphere affect different types of electromagnetic waves?

  It is transparent to visible light but not to gamma rays
• What are the risks associated with different types of electromagnetic radiation?

  • Ionizing radiation: cancer risk
  • UV radiation: skin cancer, sunburn
  • Infrared: skin burns
  • Microwaves: heating of internal cells
  • Radio waves: generally no risk
• How are different types of electromagnetic waves produced?

  • Radio waves: oscillating electrical currents
  • Microwaves and infrared: vibrations of atoms
  • Visible light: electron transitions between energy levels
  • UV, x-rays, gamma rays: processes involving atomic nuclei
• What are the similarities and differences among electromagnetic waves?

  Similarities:

  • Travel at the speed of light in a vacuum
  • Can travel through a vacuum

  
  

  Differences:

  • Vary in frequency and wavelength
  • Different absorption properties in materials
• What happens to an object as it gets hotter in terms of emitted radiation?

  It emits higher intensity and shorter wavelength radiation
• What is the relationship between temperature and the color of glowing objects?

  Hotter objects glow red, then orange, then yellow
• How does the absorption and emission of heat vary with the color of an object?

  • Matte black: best emitter and absorber
  • Shiny white: worst emitter and absorber
  • Shiny black: less efficient than matte black
  • Matte white: reflects heat well
• What happens to your temperature if you radiate more energy than you absorb?

  Your temperature will decrease
• What is the greenhouse effect related to in terms of energy absorption?

  Earth absorbs more energy than it radiates
• What are the main areas of light that need to be understood?

  1. Reflection
  2. Refraction
  3. Total internal reflection
• What color should a radiator be painted for maximum heat efficiency?

  Matte black
• Why do people wear white t-shirts on hot days?

  They absorb less heat
• What is the order of best to worst absorbers of heat?

  Matte black, white
• Why are houses in hot countries often painted white?

  To reflect heat and stay cooler
• What are the three main areas of light to know about?

  Reflection, refraction, total internal reflection
• What happens during reflection of light?

  Light bounces back at the same angle
• What is the law of reflection?

  Angle of incidence equals angle of reflection
• What is specular reflection?

  Reflection from a flat shiny surface
• What is diffuse reflection?

  Reflection from a rough surface
• What is refraction?

  Bending of light between different media
• What happens to light when it enters a denser medium?

  It bends towards the normal
• What is total internal reflection?

  Light reflects completely within a medium
• What is the critical angle?

  Angle of incidence for total internal reflection
• What happens at the critical angle?

  Angle of refraction is 90 degrees
• What is dispersion in light?

  Separation of light into colors
• What are the primary colors of light?

  Red, green, blue