homework: C and E

Apologies to C-block for not posting this sooner. E-block, this is for Friday's class.

Before next class, find the definitions of:

focal point (or focal length)

thin lens (or mirror) equation - show the equation and tell what the variables represent.

Thanks very much. If you do not get to it, because you expected it last night, I understand.

In the lab, we will take this approach:

1. Set up optical bench, using a convex lens first. Your "object" will be a candle. Find a theoretical focal length, using the method discussed in class.

2. Vary the object distance (do) and note how the resulting images (if there are images) change.

3. Watch for these things, and make notes (in a table). Is the image:

a. bigger, smaller or same size as object

b. right-side up or upside down

c. real or virtual

d. where is the image located (di)?

4. You will repeat this for a concave lens, concave mirror and convex mirror.

5. In general, you will be seeking to determine how lenses and mirrors form images, when they form images and how they form images.

6. The lens/mirror equation is very good for making predictions as to how images are formed (and what types of images are formed). You will use the lens equation to calculate an experimental focal length and compare it to your theoretical focal length (with percent error).

7. Other lab questions will be posted.