Analysis, Part 2: ray-tracing method procedure – PASCO OS-8459 Beginning Optics System User Manual

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B e g i n n i n g O p t i c s S y s t e m

E x p e r i m e n t 9 : A p p a r e n t D e p t h

Figure 9.2

With both eyes, look down through the top of the rhombus. Does the line viewed
through the rhombus appear to be closer? Close or cover one eye, and move your
head side to side. Do you see parallax between the line viewed through the rhom-
bus and the line viewed directly?

In this step, you will hold a pencil near the rhombus to determine the position of
the apparent line. When the pencil and the apparent line are at the same distance
from your eye, there will be no parallax between them.

While looking down through the rhombus (with one eye), hold a very sharp
pencil as shown in Figure 9.3 so it appears to be lined up with the line inside the
rhombus. Move your head left and right to check for parallax. Move the pencil up
or down and check again. When there is no parallax, mark that point. (Hold the
rhombus with your free hand, press the pencil tip gently against the side of the
rhombus and twist the pencil to make a light mark. Erase the mark after you have
finished this experiment.)

Analysis

Measure the distance from the top of the rhombus to your pencil mark. Record
this apparent depth, d, in the first row of Table 9.1.

Measure the thickness, t, of the rhombus and record it in Table 9.1.

Use Equation 9.1 to calculate the index of refraction and record your result in
Table 9.1.

Part 2: Ray-tracing Method

Procedure

Place the light source in ray-box mode on a white sheet of paper. Turn the wheel
to select five parallel rays. Shine the rays straight into the convex lens. Place the
mirror on its edge between the ray box and the lens so that it blocks the middle
three rays, leaving only the outside two rays (as in Figure 9.4, but do not put the
rhombus there yet).

Note: The lens has one flat edge. Place the flat edge on the paper so the lens stands stably
without rocking.

Table 9.1: Results

Part 1: Parallax method

Part 2: Ray-tracing method

Paper

Rhombus

Line

Look

down

Hold pencil

still

Move eye

side to side

Figure 9.3