Name : ____________________________________
Date: _________________
LENSES
Section A: Vocabulary
A piece of glass (or other transparent material) that can bend
parallel rays of light so that they cross or appear to cross, at a
single point.
A lens that is thickest in the middle, causing parallel rays of
light to converge to a focus. Also known as convex lens.
A lens that is thickest in the middle, causing parallel rays of
light to converge to a focus. Also known as converging lens.
A lens that is thinnest in the middle, causing parallel rays of
light to diverge. Also known as concave lens.
A lens that is thinnest in the middle, causing parallel rays of
light to diverge. Also known as diverging lens.
The line joining the centres of curvature of the surfaces of a
lens.
For a converging lens, the point at which a beam of light
parallel to the principal axis converges. For a diverging lens,
the point from which such a beam appears to come.
The distance between the center of a lens and either focal
point.
An image that is formed by converging light rays and that can
be displayed on a screen.
A diagram showing rays that can be drawn to determine the
size and location of an image formed by a mirror or lens.
Section B: Parts of Lens
Name type of the lens on diagram below and label parts of it.
Section C: Standard Rays
In ray diagrams of convex lens, any two of the following rays
are needed to fix the image position and size.
1
Any ray through the centre passes
straight through the lens.
2
A ray parallel to the principal axis
passes through F after leaving the
lens.
3
A ray through F’ leaves the lens
parallel to the principal axis.
Must use pencil and
ruler for drawing a ray
diagram!