Exercise 2: Setting up the experiment

Setting up the Experiment

The setup involved in this experiment is more involved than the previous labs. You may find it useful to follow along with this video:

Place a piece of paper on your sheet of cardboard and tape it down. With a pencil, divide your paper in quarters, making sure the lines meet in the middle at 90 degrees.

Use your protractor to draw an additional line at 45 degrees, extending from the center of your sheet. These lines will define your line of sight and will be the angle of incidence. Your sheet should look like this:

Place your clear box on your sheet with one side along the line labeled A. Trace an outline of your box and stick two paperclips into the straight lines (or pins if you have them) into your 45 degree line. We find that you can either push your paperclips or pins directly into cardboard, or you can bend the paperclip into upside-down T-shape. Do whatever you find easiest, the main thing is that you can easily look along the vertical segment to make a line-of-sight as shown in the figure below.

Now your sheet should look like this:

Initial Observations

Now that your experiment is set up, let’s make some initial observations.

First, look through the clear box along the line of sight that you marked with two paperclips/pins (here the paperclips/pins are on the opposite side of the box from where you are viewing i.e. you look through the box to see the paperclips/pins on the other side). Make sure the two paperclips/pins are perfectly in line as you look through the clear box – this will ensure your line of sight is at exactly 45 degrees to the plane of the box. Since air is filling both the inside and outside of the box, there should be little to no optical distortion.

Now, fill your box half-way with water so that the bottom half of the paperclips/pins appear under the water, and the top of the paperclips/pins are above the water. Repeat your observation. As you look through the box towards the paperclips/pins on the other side, what do you see? The paperclips/pins should look “cut and shifted” This is the effect you will be exploring in the next exercise.