physic lab report

Instructions for Use of

2643C ED-SET@ MIRCROWAVE OPTICS ACCESSORIES SET

2643C ED-SET Microwave Optics Set Mark 2B

Shown with 2643A-10 Transmitter and 2643B-10 Receiver

TABLE OF CONTENTS

Page

Description……………………………………………………………………..………2

Illustrated Parts List…………………………………………………….……….……..2

Assembly Instructions…………………………………………………..……………..3

Initial Operating Instructions………………………………………………....…..……4

EXPERIMENTS:

2. Measurement of Polarization………………………………..………………………5

3. Verification of Law of Reflection……………………………………...……………5

4. Measurement of Standing Waves…………………………………..………………..6

5. Measuring the Index of Refraction………………………….………………………7

APPENDIX 1: 2643A-10 Transmitter Mark 2G ED-SET Microwave Optics Kit…....9

APPENDIX 2: 2643B-10 Receiver Mark 2G ED-SET Microwave Optics Kit……….9

DESCRIPTION:

The 2643C ED-SET Microwave Optics Accessory Set Mark 2B is a complete set of components intended for use with a microwave transmitter and receiver to teach students the principles of optics using 3-cm wavelength microwaves as the “optical” medium. Specifically, the accessories are designed to be used with the 2643A-10 Microwave Transmitter, Mark 2B and the 2643B-10 Microwave Receiver, Mark 2B. It is also fully compatible with the former 2643A Microwave Transmitter, Mark II, and the 2643B Microwave Receiver, Mark II.

This set consists of a goniometer with four arms having tracks for the microwave transmitter and receiver and two positioning attachments for use with these devices. Also provided are one single slit plate, one double slit plate, one quadruple slit (half-reflector) plate, two combination full reflectors (Fabry-Perot plates), one polarization grid, one probe, one refraction tank, a supply of polyethylene beads, sand, and plastic bags.

ASSEMBLY INSTRUCTIONS:

A—The Goniometer

Place the goniometer base on a flat, smooth work surface.
Mount three of the four goniometer arms on the center bushing of the goniometer base in any sequence.
Place the goniometer protractor scale on the base bushing over the arms, and then engage the pin protruding from the underside of the scale in the mating hole of the arm on which you will place the transmitter. This fixes the protractor scale to 0o relative to the transmitter.
Place the goniometer rotary platform on the bushing, over the protractor scale.
Place the rotary platform accessory holder on the rotary platform as required, engaging the pins in the mating holes.

B—The Transmitter

Refer to the instruction manual included with 2643A-10 Transmitter for operating instructions. Appendix 1

C—The Receiver

1. Refer to the instruction manual included with 2643B-10 Receiver for operating instructions. Appendix 2

D—Recommended Setup

It is convenient to place the transmitter on the arm to the left of the user in most experiments. This arrangement permits placing the receiver on the right arm, providing maximum visibility of the receiver meter. The receiver and transmitter are arranged with the horns facing each other.
Place the arms at 90o to each other, with the transmitter and receiver 180°from each other. Note that each arm is equipped with two different centimeter scales. One scale starts at zero cm and indicates the distance from the axis of rotation to the aperture plane of either horn when attached to the transmitter or receiver. The other scale starts at 15 cm and indicates the distance from the axis of rotation to any accessory mounted in the sliding accessory holder. An arrow on the lower part of the horn side of the transmitter and receiver, and an arrow on the flat surface of the sliding accessory holder, indicate which scale is to be used.

E—The Accessories

The positioning attachments can be installed as follows:
1. Loosen the locking screw by turning the wing nut counterclockwise.
2. Turn the large knurled knob on the position attachment until the long lead screw is approximately centered in the U-shaped frame.
3. Place the transmitter, receiver, or sliding accessory holder on one of the arms in the position required for the experiment to be performed.
4. Place the positioning attachment of the arm so that the part to be positioned is between the positioning attachment and the goniometer axis of rotation. The large knurled knob on the positioning attachment should be furthest from the goniometer axis of rotation.
5. Engage the small round foot on the end of the positioning attachment lead screw in the shoe of the sliding accessory holder, transmitter, or receiver, as the case may be.
6. Lock the positioning attachment to the radially-rotatable arm by turning the wing nut clockwise until it is moderately tight.
7. Turn the large knurled knob through exactly 360o and not that the movement will be exactly 0.1 cm (1 mm) or one minor division on the arm scale. There are 100 grooves on the knob, and therefore rotating the knob one groove will move the attached part 0.1 mm. In this way, by counting fraction of a turn, positions on the arm can be determined very accurately when necessary. Effects of backlash must be eliminated by taking out any existing play between parts before counting the turns of the large knurled knob.
The full reflector, the half reflector, the single slit plate, the double slit plate, and the polarization grid each have a small hole above their straight edge which should be placed downward in the rotary platform accessory holder or the sliding accessory holder. This hole should be centered in the “V” notch of the accessory holder to ensure centering of the accessory.

Figure 1

INITIAL OPERATING INSTRUCTIONS:

Assemble the equipment as described in the Assembly Instructions.
Do not place your hand or any other object within the beam path while making measurements, since doing so would cause inaccurate meter readings.

Figure 2

EXPERIMENT 2: MEASUREMENT OF POLARIZATION

Reinstall the rotary platform accessory holder and arrange the components as shown in Figure 2.
Place the polarization grid in the rotary platform accessory holder with the grid in a horizontal position (vertical polarization) and record the receiver reading.
Repeat step 2, except rotate the polarization grid so that the grid is 45o from the horizontal by placing the appropriate straight edge of the polarization grid in the rotary platform accessory holder. Record the receiver reading.
Repeat step 2, except with the grid in a vertical position (horizontal polarization). Record the receiver reading.
The ED-SET 3-cm microwaves are vertically polarized, similar to polarized light. Note that the receiver readings decrease as the polarization grid is rotated from horizontal to vertical.

When the grid is aligned in a vertical position, the microwaves set up eddy currents, expending energy in doing so. When the grid is in a horizontal position, the conductive path to set up eddy currents is not present, so the microwaves pass through unattenuated. This is directly analogous to light passing through a polarizing filter. In this case, however, light waves expend energy when they excite the lattice structure of the crystals oriented parallel to the electric field of the incoming light. When these crystals are oriented perpendicular to the electric field of the incoming light, no opportunity exists to excite the crystal lattice, and so the light passes through without a reduction of intensity.

Reflector

Figure 3

EXPERIMENT 3: VERIFICATION OF LAW OF REFLECTION

Arrange the components as shown in Figure 3.
Set the reflector so the transmitter has an angle of incidence of 45° to the reflector. Slowly rotate the receiver arm until a peak reading is obtained on the receiver. Is the angle of incidence equal to the angle of reflection as stated in the Law of Reflection? Repeat the experiment using different angles.

Figure 4

EXPERIMENT 4: MEASUREMENT OF STANDING WAVES

Arrange the components as shown in Figure 4.
This arrangement will create a standing-wave pattern between the transmitter and the full reflector. A portion of the wave pattern will be picked up by the probe plate and reflected to the receiver.
Using the sliding accessory holder without the positioning attachment, starting at the end of the goniometer arm, slowly move the reflector towards the transmitter until a peak reading is observed on the receiver. Record the position of the reflector.
Continue moving the reflector slowly towards the transmitter, recording each position that produces a peak reading on the receiver. Repeat until 11 positions have been recorded. This provides ten distances between the readings. The average distance between the “peaks” represents ½ λ of the standing wave.

Figure 5

EXPERIMENT 5: MEASURING THE INDEX OF RERACTION

Remove the rotary platform accessory holder and arrange the components as shown in Figure 5.
Remove and fill the refraction tank with the materials to be measured (dry sand or polyethylene beads) using the plastic bag provided to facilitate handling.
Position the refraction tank on the rotary platform so that its bottom straightedge is aligned with line III-IIII and its indicating arrow is aligned with line B-D.
Adjust the goniometer rotary platform with the refraction tank to set an angle of incidence of 45°.
Rotate the receiver arm until a peak receiver reading is obtained. Ensure the arm is rotated over a wide enough arc to ensure the largest peak reading is identified.
Carefully remove the refraction tank and read the angle of refraction.
Calculate the index of refractions, sin i/sin r, for the materials used.
Repeat the experiment using two other angles of incidence at least 10o apart.

Eq<sin(tha)=n2 sin(tha)

N=sin(thaI) 30 /sin(thaR) 50

APPENDIX 1: INSTRUCTIONS FOR THE USE OF 2643A-10 TRANSMITTER, MARK 2B ED-SET MICROWAVE OPTICS KIT

OPERATION:

Power Switch. A slide switch, located on the top of the case, is used to apply power to the circuitry. When in the ON or forward position, the circuitry is energized and the pilot light will be lit. When the slide switch is in the OFF or rear position, power is removed from the circuitry.

Pilot Light. An indicator light, located on the top of the case, lit when power is applied to the circuitry.

Fuse. An in-line fuse located on the printed circuit board inside the case. If needed, gently pry the fuse out of the clip holder and replace with a 3/10A, Slo-Blo, 3 AG fuse only.

Operation. With the Power Switch in the OFF position, insert the power line cord firmly into its matching polarized receptacle. This ensures that power to the instrument is properly polarized and grounded. The case is grounded through connection to the NEMA receptacle. The instrument is designed to be operated by connection to the power source by this method only. Failure to do so creates a potential shock hazard and may adversely affect the performance of the instrument.

When the Power Switch is place in the ON position, microwaves are generated and transmitted through the horn. No adjustments or warm up time are required. It is recommended that microwaves be generated only during the course of an experiment.

Calibration. None required.

Hazards. The 2643A-10 Microwave Transmitter derives its power from the AC line. The line voltage is present at the power input sections of the circuit and may present a hazard if normal precautions are not taken. These precautions include use of properly grounded circuits and use of standard connectors only.

This device emits microwaves at a level which is considered safe. However, good laboratory practice dictates that exposure to any radiation be kept to an absolute minimum. Generate microwaves only during the course of the experiment. Do not point microwaves directly at the body. This is especially true of the eyes and testes. Anyone using the transmitter who wears an electronic heart pacemaker or similar device should consult a physician before use as the RF (radio frequency) radiation from this transmitter may adversely affect the electronics of the device.

APPENDIX 2: INSTRUCTIONS FOR THE USE OF 2643B-10 RECEIVER, MARK 2B ED-SET MICROWAVE OPTICS KIT

OPERATION:

Power Source. The Receiver requires no internal power source for normal operation. However, to detect weak signals, an external amplifier may be required to provide sufficient amplification for meter display.

Gain Control Knob. A potentiometer control located on the top of the case. Used to attenuate the signal received so that it can be displayed within the full scale deflection of the meter. The signal is totally attenuated when the Gain Control Knob is turned fully counterclockwise.

Amplifier Jack. A phone jack located on the lower rear panel of the case. Used in conjunction with the 2641C Amplifier to amplify weak microwave signals received after deflection from the Bragg Diffraction simulated crystal.

Meter. An analog meter located on the front panel of the case. Graduated in arbitrary lower units from 0 to 100 and in decibels (dB) to determine attenuation. A decibel is equal to 10 times the common logarithm of the ratio of the attenuated versus unattenuated signal.

Use.

When no microwave field is present, adjust the zero of the meter by turning the small plastic screw on the lower part of the meter. Use a small screwdriver and turn either clockwise or counterclockwise until the pointer is on zero.
Turn the Gain Control Knob of the Receiver fully counterclockwise and turn the Power Switch of the Transmitter to the ON position. Point the horns of both the Transmitter and Receiver at each other and separate the two by a distance of about 10 centimeters or more.
Turn the Gain control Knob of the receiver clockwise until a power level of 100 is reached. A standing wave pattern is established between the Transmitter and Receiver. Moving either will change the standing wave and either increase or decrease the power received. At the beginning of each experiment, it will be necessary to readjust the Gain control Knob to display 100% power.

Hazards. The 2643B-10 Microwave Receiver derives its power for operation from the microwaves it detects. The instrument is considered safe when used according to instructions.

This device is used where microwave radiation is present. Good laboratory practice dictates that exposure to any radiation be kept to an absolute minimum. Generate microwaves from the Transmitter only during the course of the experiment. Do not point the Transmitter directly at the body.