EYES AND SUBTOPICS

• What is the formula for the mirror equation?

  $\frac{1}{d_o} +$$\frac{1}{d_i} =$$\frac{1}{f}$
• What does $d_o$ represent in the mirror equation?


  Object Distance
• What does $d_i$ represent in the mirror equation?


  Image Distance
• What does $f$ represent in the mirror equation?


  Focal Length
• What does the magnification formula $M =$$\frac{H_i}{H_o} =$$-\frac{d_i}{d_o}$ represent?


  Relationship between image and object height
• What does a positive focal length indicate?

  Converging lens
• What does a negative image distance indicate?

  Virtual image
• What does a positive image height indicate?

  Upright image
• What does a magnification less than 1 indicate?

  Reduced image size
• What are the main functions of the cornea?

  • Outer dome covering the eye
  • Bends light rays to focus on retina
  • No blood vessels; gets oxygen from air
  • Contains sensitive nerves for blinking
• What is the appearance of the pupil?

  Black hole in the eye
• Why do red eyes appear in photos?

  Light bounces off blood vessels
• What is the function of the iris?

  • Colored part of the eye
  • Protects from excessive brightness
  • Adjusts pupil size based on light
• What is the size of the lens compared to aspirin?

  Aspirin-sized
• What is the primary function of the lens?

  Focuses light on the retina
• How much of the eye is visible in a mirror?

  1/6 of the eye
• What is the approximate size of the human eye?

  Size of a ping pong ball
• How many working parts does the eye have?

  Over 2 million
• What causes the eye to move?

  Six muscles in the socket
• How do the cornea and lens work together?

  • Cornea does most of the focusing
  • Lens does fine focusing for clear image
• Why are images in the back of the eye upside down?

  Lens bends the light beam
• How does the brain interpret light entering the eye?

  Turns light into nerve impulses
• What are the functions of cones in the eye?

  • Detect up to 7 million colors
  • Three types: red, green, blue
  • Allow perception of colors like magenta
• What are the functions of rods in the eye?

  • See black, white, and gray shades
  • More numerous than cones
  • Help in low light and peripheral vision
• What happens when you turn off the light?

  Rods send visual information to the brain
• How are rods and cones connected to the brain?

  Through neurons to the optic nerve
• What is the blind spot in the eye?

  Where no rods or cones are present
• What happens to electric impulses from the optic nerve?

  Travel to the brain's visual cortex
• How does the brain know the orientation of images?

  Balance system in the ears
• What is the role of the cornea in light refraction?

  • Refracts most light entering the eye
  • Biconvex shape ensures image on retina
• What is accommodation power of the eye?

  Ability of lens to change focal length
• What is myopia?

  • Nearsightedness
  • Nearby objects clear, distant blurry
  • Light converges in front of retina
• What is hyperopia?

  • Farsightedness
  • Distant objects clear, nearby blurry
  • Light focused behind the retina
• What is the minimum distance a normal eye can see clearly?

  25 cm without strain
• What is astigmatism?

  • Distorted curvature of the cornea
  • Light focused at multiple points
  • Causes blurriness in vision
• What is presbyopia?

  • Common in seniors
  • Similar to hyperopia
  • Lens loses accommodation power
• How does presbyopia affect vision?

  Nearby objects appear blurry