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Eye&lens definitions
definitions for eye and lenses junior science
Term | Definition |
---|---|
Compound Lens | Combination of two or more lenses in contact with each other |
Accommodation | Adjusting the focal length of a lens to focus near or distant objects clearly on the retina |
Short-sightedness | When distant objects cannot be seen clearly |
Long-sightedness | When near objects cannot be seen clearly |
Myopia | When near and distant objects cannot be seen clearly, only middle objects can be seen clearly. |
Pupil | a hole in the eye that allows light through |
Lens | The part of the eye that refracts light from the object so the image forms on the retina |
extraocular muscles | muscles around the eye ball that control eye movement |
iris | the coloured ring of muscle that contracts to let less light in and relaxes to let more light in. |
optic nerve | a bundle of nerves at the back of the retina that transmits the image to the brain |
retina | a layer of cells at the back of the eye where the image forms |
cones | receptors on the retina that detect colour |
rods | receptors on the retina that detect light and dark/black and white |
cornea | clear protective film covering outer eye which slightly refracts light. |
sclera | whites of the eyeball |
ciliary muscles | muscles that control the curvature of the lens and therefore its ability to focus the image on the retina |
vitreous humour | colourless fluid in the middle of the eyeball that gives the eyeball its shape |
convex lens | a lens that bulges outwards on both sides and is used to magnify objects eg magnifying glass. |
concave lens | a lens that bulges inwards on both sides and is used to make objects appear smaller eg glasses for short sighted people. |
prism | a triangular 3D object of glass or plastic that can refract and disperse light |