topic 4

Subdecks (2)

Cards (34)

  • pupil - the whole in eyes where light comes in
  • iris - a band of muscle that controls the size of the pupil, which controls the amount of light entering the eye
    • pupil dilates to allow more light in (dim light)
    • constricts to let less light in (bright light)
  • aperture - whole where light comes into a camera
  • diaphragm - device that changes the size of the aperture
  • shutter - lies behind the aperture acts like a set of doors. The longer the shutter remains open, the more light enters the camera and strikes the film
  • diagram of camera
    A) film
    B) shutter
    C) aperture
    D) lens
  • retina - a layer that is filled with photoreceptors
  • photoreceptors - cells sensitive to light
  • rods - Highly sensitive to light, they can function in very low light
  • cones - less sensitive than rods but are responsible for colour vision
  • how images are formed
    • When light strikes the retina, the photoreceptors are stimulated
    • They send messages to the optic nerve (at the back of the eye) 
    • The optic nerve then passes the message onto the brain
    • The brain then translates the message into an image
  • film - light sensitive material at the back of a camera, changes chemically
    • The images formed on both the retina and on the camera film are upside down (inverted)
  • focusing light
    • ciliary muscles attached to the lens contract and relax to change the shape of the lens
    • Changing the shape of the lens adjusts the focal length so that light forms a focused image on the retina
  • farsightedness - when people cannot see close objects clearly, images form to FAR behind the retina
  • nearsightedness - when people cannot see far things clearly
    • light rays converge to early
  • nearsighted - concave lenses
  • farsighted - convex lenses
  • laser eye surgery
    • changes shape of cornea
    • cornea acts like a corrective lens
  • human eye
    A) ciliary body
    B) iris
    C) lens
    D) pupil
    E) cornea
    F) sclera
    G) retina
    H) optic. disk
    I) optic nerve