Topic 5 – Light and the Electromagnetic Spectrum

Cards (57)

  • What do arrows in ray diagrams represent?
    Direction of light travelling
  • What is the normal in ray diagrams?
    The normal is an imaginary dashed line that is perpendicular to the surface.
  • What is the incident angle?
    The angle of the entering ray.
  • What is the reflected angle?
    The angle of the exiting ray.
  • What is the relationship between incident angle and reflection angle?
    Incident angle equals reflection angle.
  • How are angles measured in reflection?
    Angles are always measured from the normal.
  • 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)?
    TIR occurs when light passes from a denser medium into a less dense medium.
  • What happens if the angle of incidence is equal to the critical angle?
    The refracted ray will pass along the boundary and not exit the medium.
  • What is the critical angle?
    The unique angle for each two media at which TIR occurs.
  • What happens for angles larger than the critical angle?
    The light internally reflects back into the denser medium.
  • What are the outcomes when light travels from glass to air based on the angle of incidence?
    • If angle LESS than critical angle, light refracts away from normal.
    • If angle EQUAL to critical angle, light passes along boundary.
    • If angle MORE than critical angle, light reflects.
  • What is specular reflection?
    Mirror reflection following the law of reflection for a smooth surface.
  • What is diffuse reflection?
    Light hitting a rough surface is reflected at many angles.
  • What does each color in visible light represent?
    Each color is a certain wavelength in visible light.
  • What do all colors together make up?
    White light.
  • Why do opaque materials appear to have a certain color?
    They reflect only that certain color light and absorb all other colors.
  • What happens when light passes through color filters?
    All other colors are absorbed, and only a certain color is allowed to pass through.
  • What is the focal length of a lens?
    The distance between the lens and the focal point.
  • What is the focal point of a lens?
    The point where all horizontal rays meet after passing through the lens.
  • How is the power of a lens defined?
    Power of the lens is the inverse of the focal length.
  • What is the relationship between focal length and lens power?
    Shorter focal length means greater power.
  • How does the thickness of a lens affect its focal length and power?
    Thicker lens means shorter focal length, so greater power.
  • What is the shape of concave lenses?
    Concave lenses "cave" inward and are thinner at the center than at the edges.
  • What is the function of concave lenses?
    They spread light outwards and make it appear to come from the focal point.
  • How are concave lenses used in vision correction?
    They are used to correct short-sightedness by spreading out light.
  • What is the shape of convex lenses?
    Convex lenses are fatter at the center.
  • What is the function of convex lenses?
    They focus light inwards and are used for magnifying glasses and binoculars.
  • How do convex lenses help with long-sightedness?
    They focus rays closer to the eye.
  • What is a real image?
    A real image is produced at the opposite side of the lens to the object.
  • What is a virtual image?
    A virtual image appears to come from the same side of the lens as the object.
  • When does a virtual image occur?

    A virtual image occurs if the object lies closer to the lens than the focal point.
  • What do all electromagnetic waves do?
    They transfer energy from a source to an observer.
  • What type of waves are electromagnetic waves?
    They are transverse waves.
  • How fast do all electromagnetic waves travel in a vacuum?
    They all travel at the same speed.
  • Do electromagnetic waves need particles to move?
    No, they do not need particles to move.
  • How do materials interact with electromagnetic waves?
    Materials interact differently depending on the wavelength.
  • What can our eyes detect in terms of electromagnetic waves?
    Our eyes can only detect visible light.
  • What happens to wavelength and frequency in electromagnetic waves?
    As wavelength decreases, frequency must increase.