II. Lenses
A. Refractive lenses
1. Lens: a carefully ground or molded piece of transparent material that refracts light rays to form an image 2. Diverging or concave lens: a lens that is thinner at the middle and thicker on the sides a. Parallel light beams passing through diverge (or spread out) b. Light does not focus on the other side 3. Converging or convex lens: a lens that is thicker at the middle and thinner on the sides a. Parallel light beams passing through it converge (or come together) b. Light comes together on the other side of the lens to form a focal point i. The distance from the lens to the focal point is called the focal length The thicker the convex lens, the shorter the focal length The further the lens from the light source, the shorter the focal length 4. Lenses have many uses a. the lens in your eye b. Microscopes c. binoculars & telescopes d. cameras e. magnifying lenses f. CD players |
Lenses
Click on the picture to see how light bends through different lenses
Concave or diverging lens
Concave lenses diverge light
Convex or converging lens
Convex lenses converge light towards a focal point. Click on the picture to play with an interactive where you can change the size of the lens and how much it refracts to see what happens to an image. Click here to go to another interactive slider that better demonstrates how magnification occurs when the object is within the focal point, OR play with the interactive below.
Also, the video below does a great job of explaining how convex lenses magnify and flip images. You are NOT required to know this in this kind of detail, but you may want to know more! |
Videos on Lenses - I'm going to have to replace these!
Questions on Lenses & Eyes
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