Experiment 9: two-slit interference, Introduction, Procedure – PASCO OS-8500 INTRODUCTORY OPTICS SYSTEM User Manual
Page 29
012-02744K
Introductory Optics System
®
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EQUIPMENT NEEDED:
-Optics Bench
-Light Source
-Diffraction Plate
-Diffraction Scale
-Ray Table Base
-Slit Mask
Experiment 9: Two-Slit Interference
Figure 9.1 Equipment Setup
Introduction
What is light? There may be no complete answer to this question. However, in certain circumstances,
light behaves exactly as if it were a wave. In fact, in this experiment you will measure the wavelength of
light, and see how that wavelength varies with color.
In two-slit interference, light falls on an opaque screen with two closely spaced, narrow slits. As
Huygen’s principle tells us, each slit acts as a new source of light. Since the slits are illuminated by the
same wave front, these sources are in phase. Where the wave fronts from the two sources overlap, an
interference pattern is formed.
Procedure
Set up the Equipment as shown in Figure 9.1. The Slit Mask should be centered on the Component
Holder. While looking through the Slit Mask, adjust the position of the Diffraction Scale so you can see
the filament of the Light Source through the slot in the Diffraction Scale.
Figure 9.2 Geometry of Two-Slit Interference
Diffraction Scale
Slot
Ray Table
Base
Diffraction
Plate
Window
Slit Mask
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DIF
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Retina of your
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Diffraction Plate
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Diffraction Scale
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λ