Card Set Information
Lenses, application to eye, etc
What are the
two types of lenses
Converging lens (Convex)
Diverging lens (Concave)
What are converging lenses?
They are convex lenses.
They make parallel light rays converge/meet at a particular point.
The lens is thick in the middle and thin at the ends.
What are diverging lenses?
They are concave lenses.
They make parallel light rays diverge after going through it.
The lens is thin in the middle and thick at the ends.
Images formed by converging lenses
As long as the object is outside the focal point, the image is real and inverted.
When the object is inside the focal point, the image is virtual and upright.
When the object is at 2F, the image formed is the same size as the object.
List down formulas to find
Linear magnification, m
How are images formed in our eye?
Light falling on object is reflected in all directions.
Some reflected rays enter the eye.
These light rays are bent (refracted) by the cornea, vitrous humor, lens, etc.
Bent light rays meet on the retina.
An inverted image is formed.
Images on retina creates impulses, which will travel to the brain by sensory neurones.
Brain interprets impulses so that the viewer sees the object right way up.
Name the two types of eye defects.
Long-sight - can see far objects clearly, but near objects appear blur. (corrected by converging lens)
Short-sight - can see near objects clearly, but far objects appear blur. (corrected by diverging lens)
Changes of lens shape
When I try to focus on a distant object, my lens become thin
When I try to focus on a nearby object, my lens become fat