1. Lenses

2. Lenses
A lens is made out of transparent material with two sides, either convex or concave
A convex lens will have two sides that are thin on top and thicker on the edges
A concave lens will have two sides that are thick on the top and thinner on the edges

3. Lenses
For convex and concave lenses, the mirror equation and the equation for magnification still holds.
do will be positive for real objects, negative for virtual objects
di will be positive for real images, negative for virtual images
The focal length will be positive for convex lenses, negative for concave lenses

4. Lenses The difference between real and virtual images
A real image is an image produced from where the light rays actually converge
A virtual image is made from where the light rays appear to be coming from

5. Lenses
A convex lens will make a virtual image if the object is in between the focal point and the lens.
A convex lens will make a real image if the object is behind the focal point.
A concave lens cannot produce a real image, because the rays diverge

6. Lenses
Chromatic Aberration – An object viewed through a lens appears ringed with color, because the edges of a lens act like a prism.
An achromatic lens can cancel out chromatic aberration. This would include a convex/concave mix to keep the color from diverging

7. Lenses
Example 1 (#4 from the book): An old “magic trick” used a concave mirror to project an image the same size as the object and at the same distance from the mirror. If the object is 25cm away from the mirror, what should the radius of curvature of the mirror?

8. Lenses
Example 2: A stamp collector wants to magnify images by 4.0 when the object is 3.5cm away from the lens. What should the focal length be for the lens?

9. Lenses
K so here are some more problems in the worksheet. Then the homework is
Pg 374: 2,3
Pg 376: 5,6
Pg 378: 11,12
Pg 381: 13,14
Pg 383: 17,19
DUE 3/15 Tuesday