Lenses
We use lenses everyday in our daily lives. Check out this video for some examples.
Converging Lenses
A converging (convex) lens is called a converging lens because any set of parallel rays that strike the lens will converge at a single point on the opposite side of the lens.
Properties of Convex Lenses
The principal axis (PA) runs through the centres of curvature.
The upright axis perpendicular to the PA is the vertical axis (V).
Unlike mirrors, lenses have two spherical surfaces, two radii of curvature and the light passes through a refracting medium in both directions.
Parallel rays that pass through a converging lens converge to a point on the other side of the lens. This is the focal point (F) (there is a focal point on each side).
The distance from the vertical axis to the focal point is the focal length (f).
To see the image, you must put your eye in the path of the diverging rays. If you place your eye where the rays have yet to converge, you will not see the image.
Ray Diagram for Convex Lenses
To determine the kind of image formed by a convex lens, draw light ray diagrams.
Watch this video (start at 1:55) to see ray diagrams being drawn.
Practice Answer Key:
Question of the Day #12: Complete p. 355 # 7. Send me a picture of your answer on Edsby.
