Physics - Concave mirrors

• Plane mirrors


  Produce images that are the same size, altitude (upright), same distance from the mirror and are virtual

  
• Not all images produce images of the same, shape and orientation

  
• Concave (converging) mirror

  • Mirror whose surface reflects inward
  • If you cut out a section of a basketball and put a reflect surface on the inside that would be a concave mirror

  
• Terminology for concave mirrors

  • Centre of curvature: the centre of the sphere whose surface has been used to make the mirror. This is labelled "C".
  • Principal Axis: is the line going through the centre of curvature and the centre of the mirror.
  • Vertex: The point where the principle axis meets the mirror. This is labelled "V".

  
• Concave mirror image formation


  1. Parallel to mirror then through F

  2. From F and then parallel to principal axis

  3. From C to mirror and then back again

  
• Properties of image between F and mirror

  • Size: larger
  • Altitude: upright
  • Location: behind mirror
  • Type: virtual

  
• Examples of concave mirrors

  • Beauty and shaving mirrors
  • Radar antenna
  • Solar ovens
• Radar antenna


  1. Pulse of radio waves hit the antenna and send out toward the sky

  2. Any returning radio waves will hit the focal point

  3. Detector located at focal point

  
• Properties of image between C and F

  • Size: larger
  • Altitude: inverted
  • Location: in front of mirror
  • Type: real

  
• Properties of image beyond C

  • Size: larger
  • Altitude: inverted
  • Location: in front of mirror
  • Type: real

  
• As rays are parallel they were never intersect