Physics - Topic 5 - Light and the Electromagnetic Spectrum

• 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 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
• From where are angles measured in ray diagrams?

  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 equals 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
• What happens for angles larger than the critical angle?

  The light internally reflects back into the denser medium
• What are the outcomes of light at different angles in relation to the critical angle when passing from glass to air?

  • 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 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?

  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 to colors when using 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 is the inverse of the focal length
• What happens to the power of a lens as the focal length decreases?

  The power increases
• How does the thickness of a lens relate to its focal length and power?

  A thicker lens means a shorter focal length, resulting in greater power
• What is the shape of concave lenses?

  Concave lenses "cave" inward
• How do concave lenses affect light?

  They spread light outwards
• What is the effect of concave lenses on vision?

  They are used to correct short-sightedness
• What is the shape of convex lenses?

  Convex lenses are fatter at the center
• How do convex lenses affect light?

  They focus light inwards
• What are convex lenses used for?

  They are used for magnifying glasses and to correct long-sightedness
• What is a real image?

  An image produced at the opposite side of the lens to the object
• What is a virtual image?

  An image that appears to come from the same side of the lens as the object

  
• When does a virtual image occur?

  When the object lies closer to the lens than the focal point
• What do all electromagnetic waves do?

  Transfer energy from source to observer
• What type of waves are electromagnetic waves?

  They are transverse waves
• How fast do all electromagnetic waves travel in a vacuum?

  At the speed of light
• Do electromagnetic waves need particles to move?

  No, they do not need particles to move
• How do materials interact with electromagnetic waves?

  They 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 the speed of electromagnetic waves in space?

  All waves have the same velocity (speed of light)