PASCO Specialty & Mfg. OS-8459 Manuel d'utilisateur télécharger pdf (Page 23)

Model No. OS-8459 Experiment 9: Apparent Depth

Experiment 9: Apparent Depth

Purpose

In this experiment, you will use two different methods to measure the apparent depth

of the acrylic rhombus. You will also determine the index of refraction of acrylic by

comparing the apparent depth to the actual depth.

Theory

Light rays originating from the bottom surface of a block of

transparent material refract at the top surface as the rays

emerge from the material into the air (see Figure 9.1). When

viewed from above, the apparent depth, d, of the bottom sur-

face of the block is less than the actual thickness, t, of the

block. The apparent depth is given by

(eq. 9.1) d = t/n

where n is the index of refraction of the material.

Part 1: Parallax Method

Background

Place this page flat on the table in front of you. Hold a pencil horizontally a few centi-

meters above the paper. With one eye closed or covered, look down at the pencil and

move your head side to side (without moving the pencil). Notice how the pencil

appears to move relative to the words printed on the paper; this phenomenon is known

as parallax. Now hold the tip of the pencil on the paper and check for parallax. When

there is no parallax between to objects, they are at the same distance from you.

Procedure

1. Place a blank sheet of paper flat on the table. Use a straight edge and pencil to

draw a vertical line on the paper. Place the rhombus on the paper over the line as

shown in Figure 9.2.

Required Equipment from Beginning Optics System

Light Source

Rhombus from Ray Optics Kit

Convex Lens from Ray Optics Kit

Mirror from Ray Optics Kit (used to block rays)

Other Required Equipment

Metric ruler

White paper

Very sharp pencil

air

= 1

n > 1

bottom

top

Figure 9.1

1 2 ... 18 19 20 21 22 23 24 25 26 27 28 ... 50 51

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PASCO Specialty & Mfg. OS-8459 Manuel d'utilisateur Page 23