Topic 5-Light and The Electromagnetic Spectrum

• What do arrows in ray diagrams indicate?

  Direction of light travelling
• What is the normal in ray diagrams?

  An imaginary dashed line perpendicular to surface
• What is the incident angle?

  Angle of the entering ray

  
• What is the reflected angle?

  Angle of the exiting ray
• What is the relationship between incident angle and reflected angle?

  Incident angle equals reflected angle
• How are angles measured in reflection?

  From the normal line
• What happens to light when it enters a denser material?

  It bends towards the normal
• What happens to light when it enters a less dense material?

  It bends away from the normal
• What is total internal reflection (TIR)?

  Light passing from denser to less dense medium
• What occurs at the critical angle?

  Refracted ray passes along the boundary
• What happens if the angle of incidence is less than the critical angle?

  Light refracts away from the normal
• What happens if the angle of incidence is equal to the critical angle?

  Light passes along the boundary
• What happens if the angle of incidence is more than the critical angle?

  Light reflects back into the medium
• What is specular reflection?

  Mirror reflection from a smooth surface
• What is diffuse reflection?

  Reflection at many angles from a rough surface
• What does each color in visible light represent?

  A certain wavelength of light
• What is the composition of white light?

  All colors of visible light combined
• Why do opaque materials appear to have a certain color?

  They reflect only that color light
• What happens to colors in color filters?

  Only a certain color passes through
• What is the focal length of a lens?

  Distance between lens and focal point
• What is the focal point of a lens?

  Point where horizontal rays meet
• How is the power of a lens calculated?

  Inverse of the focal length
• What happens to lens power with shorter focal lengths?

  Power increases with shorter focal lengths
• What is the shape of concave lenses?

  Thinner at center than at edges
• What is the function of concave lenses?

  Spreads light outwards
• How do concave lenses correct vision?

  They spread light to focus on retina
• What is the shape of convex lenses?

  Thicker at center than at edges
• What is the function of convex lenses?

  Focuses light inwards

  
• What are convex lenses used for?

  Magnifying glasses and binoculars
• What is a real image?

  Image produced opposite side of lens

  
• What is a virtual image?

  Appears to come from same side as object
• What type of waves are electromagnetic waves?

  Transverse waves
• What is the speed of electromagnetic waves in a vacuum?

  All travel at the same speed
• How do electromagnetic waves transfer energy?

  From source to observer
• How do materials interact with electromagnetic waves?

  Depends on the wavelength
• What happens as wavelength decreases in electromagnetic waves?

  Frequency must increase
• What happens as frequency increases in electromagnetic waves?

  Energy of the wave increases
• How does temperature affect radiation emission?

  Higher temperature means more intense radiation
• What must a body do to maintain constant temperature?

  Radiate same average power it absorbs
• What happens if a body absorbs more power than it emits?

  Temperature will increase