PASCO WA-9316A Complete Microwave Optics System - Manual (Page 20)

Experiment Guide Experiment 6: Double-Slit Interference
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mitter back 50% so that the microwave radiation at the slits will have the same relative intensity. Repeat the
measurements. (You may want to try other slit spacings as well.)
Questions
1. From your data, plot a graph of meter reading versus q. Identify the angles at which the maxima and minima of the inter-
ference pattern occur.
2. Calculate the angles at which you would expect the maxima and minima to occur in a standard two-slit diffraction pattern
— maxima occur wherever d sin  = nand minima occur wherever d sin = n/2. (Check your textbook for the deriva-
tion of these equations, and use the wavelength measured in experiment 3.) How does this compare with the locations of
your observed maxima and minima? Can you explain any discrepancies? (What assumptions are made in the derivations
of the formulas and to what extent are they met in this experiment?)
3. Can you explain the relative drop in intensity for higher order maxima? Consider the single-slit diffraction pattern created
by each slit. How do these single slit patterns affect the overall interference pattern?
NOTE:
• Wavelength at 10.525 GHz = 2.85 cm.
• The experimenter’s body position may affect the results.
Table 6.1: Data
Angle Meter
Reading
Angle Meter
Reading
Angle Meter
Reading
0° 30° 60°
5° 35° 65°
10° 40° 70°
15° 45° 75°
20° 50° 80°
25° 55° 86°