Physics

• Mirrors


  Optical devices that permit the reflection of light
• Mirrors


  • Planar or spherical

  
• Plane mirrors


  Will always form an image that has the same size as the object, the light rays incident to it simply bounce back and do not change their direction with respect to how they approach the mirror, the image form is erect or upright

  
• The focal point of a plane mirror does not exist in its real side (same side as the object), it must be in the virtual side that renders the formed image as virtual

  
• When you look directly into a plane mirror, you will see the reflected images of yourself and the objects around you. If you turned the light off in a bathroom to make the room completely dark, the image will disappear. The image will only appear when the light is turned back on
• Plane mirrors


  • Produce images that appear to be as far behind the mirror as the image is in front, the only defect is the reversal effect, the right side of the object appears as the left side appears as the right - the image is flipped from left to right

  
• The letters from the word AMBULANCE were printed backwards and are reversed in sequence so that they appear in the proper orientation and order when seen in a rearview mirror
• Size and position of the image formed in a plane mirror


  Image is virtual, erect, same size as object and laterally inverted, image distance equals object distance

  
• Curved mirrors


  Commonly spherical mirrors, the reflecting surface is part of a large sphere, have a vertex, center of curvature, and principal focus

  
• Concave mirror


  • Also known as converging mirror, with a surface that curved inward like the inside of a bowl, turns parallel rays into convergent rays

  
• Uses of concave mirrors


  • Magnifying mirrors for shaving and applying makeup
  • Reflecting telescopes
  • Making the beam of light in flashlights and car headlights
• Convex mirror


  Also known as diverging mirror, with a surface that curves outward, can reflect parallel rays of light so that they apparently meet at a point behind the mirror

  
• Summary of how different mirrors form images


  • Plane mirror: Same size, erect, virtual
  • Concave mirror: Enlarged, inverted, real
  • Convex mirror: Diminished, erect, virtual

  
• Power of a mirror


  Inverse of the focal length

  
• Radius of curvature


  Twice the focal length
• Magnification of a mirror

  Ratio of image height to object height, or ratio of image distance to object distance

  
• Sign convention for image formation by mirrors


  • Plane mirror: +, no real image, -, N/A, +, not inverted
  • Convex mirror: -, no real image, -, +, +, -
  • Concave mirror: -, +, -, -, +, +

  
• Sign convention for image formation by lenses


  • Concave or diverging lens: -, +, -, -, +, +, -
  • Convex or converging lens: -, +, -, +, +, +, -

  
• Thin lens equation


  1/f = 1/d0 + 1/di, where f is focal length, d0 is object distance, and di is image distance

  
• Example 1: Concave mirror


  • Given: h0 = 5 cm, d0 = 50 cm, f = 15 cm. Solve for di and hi. di = -21.43 cm, hi = 2.143 cm

  
• Example 2: Diverging lens


  • Given: h0 = 10 cm, d0 = 30 cm, f = -15 cm. Solve for di and hi. di = -10 cm, hi = 3.33 cm
• Example 3: Convex mirror


  • Given: h0 = 5 cm, d0 = 10 cm, f = 15 cm. Solve for di and hi. di = -30 cm, hi = 15 cm

  
• Example 4: Converging lens


  • Given: h0 = 0.10 m, d0 = 0.75 m, f = 0.25 m. Solve for di and hi. di = 0.375 m, hi = -0.05 m
• Converging lenses concentrate refracted rays to a single point, used to create images for the eyes of individuals suffering from farsightedness. Diverging lenses scatter these rays, a pair is needed to correct the vision of those suffering from nearsightedness