**David
Deutsch
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Manhattan Center for Science and Mathematics

Summer 2001

**Wave
Nature and Wavelengths of Microwaves**

**Aim/Problem:**
1. Can we demonstrate the wave nature of microwaves?

2. Can we determine the wavelength of a microwave?

**Objectives:**** **
The student will be able to

1. Recall the wave phenomena - reflection, refraction,
diffraction, interference, and polarization.

2. Agree upon an appropriate procedure for testing whether microwaves are
waves.

3. Extend that procedure to determine the wavelength of the microwaves.
(frequency as well)

4. Compare the measured frequency to published microwave frequencies
(such as in a textbook or NYS
Regents tables).

**Materials:**** **
**Microwave Diffraction Kit** (which should include:)

- Microwave Source

- Microwave Detector

- Metal slits of varying width

- Polarizers

- Reflecting surfaces

- Meter Sticks

- New York State Physics Regents Reference Tables (or equivalent)

**Plan: **
1. Students will first be briefed in the safe use of the equipment.

2. Students will meet (briefly) to establish procedures for solving the
problem. Note that steps 1 and 2
could occur in class the day before
the lab period. **(Standards S5a, S8a)**

3. The teacher will monitor student progress in solving the
problem. In the event that a group becomes
stuck, the teacher can ask a
series of leading questions to encourage groups toward
a sensible procedure. In the approximate order that they may be relevant
some
such questions are:

- If it is a wave, what must it be able to demonstrate?

- Have you
measured a slit to detector distance? (L)

- Have you moved the detector to different locations?

- Have you measured the distance between the slits? (d)

- How will you determine the distance from the central order to the first
order? (x or sin0 = x/L)

- How will you determine the wavelength of the microwave? (use Young's
Double Slit wavelength = xd/L = dsin0)

- How might you check that wavelength? (Try a slit with different
spacing)

- Is it a longitudinal or transverse wave? ( use the polarizing filter to
determine)

- How will you find the frequency? (c = f * wavelength)

- Is your frequency comparable to those on the reference tables? (**Standards
S1f, S5b, S5e**)

4. As a post lab exercise, students can be encouraged to share results, look for
novel approaches to data collection
or presentation, average results, and
suggest improvements to the lab. (**Standard S5f**)

5. Students complete report following the conventions outlined on the handout.
The report should detail the chosen
method (procedure), present the data,
and describe a the solution to the problem. The discussion section challenges
students to infer the importance of this
lab to astronomy.
(**Standards S6b, S6c**)

6. A future lesson will review the achievements of non-visible light astronomy.

**Regents
Physics Laboratory - Microwave Diffraction**

**Problem:****
** 1. Can we demonstrate the wave nature of microwaves?

2. Can we determine the frequency of a microwave?

**Materials:**
Microwave Source
Meter Sticks

Microwave Detector
NYS Physics Regents Tables

Metal Slits
Polarizers

**Grading Rubric:**

Your report will be graded
according to the following criteria:

1. Does your report follow
the rules of standard written English?

2. Is your report neat and
easy to read?

3. Have you clearly
described the method or procedure you have used to solve the problem?

4. Have you included
appropriate data tables? Are all of your measurements recorded?

5. Have you clearly
explained and shown any calculations you needed to make?

6. Based on your data, have
you drawn a conclusion?

7. Have you included a
DISCUSSION section in which you fully address at least these questions:

a. How is microwave radiation different from visible light?

b. How are they similar?

c. Why might studies of microwave radiation be useful to astronomers?

d. What improvements could you make to this lab?

Due Date:

This lab is due at the beginning of class on ___________________________