Category Archives: Polarization

Polarized Transmission/Reflection

Demo: OP-H-PT
Pira Index: 6H 20.10

 Lab Equipment  Directions
  1.  Acrylic block
  2. marked foam board
  3. 2 binder clips
  4. transparency for OHP
  5. lab jack
  6. small lab stand and 3 finger clamp
  7. green laser pointer with sleeve
  8. small screen
  1.  Clip the foam board and prism onto the lab jack and set the screen at the end as shown.
  2. Place the lab stand with laser pointer so that its beam hits right side of the prism, resulting in reflected and refracted dots on screen. Carefully adjust lab stand location so that beam follows line on back right of foam board. Slowly rotate laser in sleeve until reflected dot nearly disappears. This line represents Brewster’s Angle, the angle of incidence at which the reflected beam is entirely polarized.
  3. Try the laser at other angles to show that the reflected beam does not disappear.


Polarized Light Reflection

Demo: OP-H-PR
Pira Index: 6H 20.12

 Lab Equipment  Directions
  1.  Chrome laser pen
  2. Small lab stand and 3 finger clamp
  3. Black sheet of reflective plastic
  1.  Arrange the set up so that when the vertical laser beam hits the plastic it is reflected onto the wall or ceiling.
  2. Rotate the laser in the finger clamp until the beam is horizontal. Notice that the projected reflection disappears.
  3. Adjusting the angle of the reflected beam will fine tune the effect.


Polarized Light

Demo: OP-H-PL
Pira Index: 6H 35.50

 Lab Equipment  Directions
  1.  table top polarizers
  2. stress specimen
  3. light source
  1.  Shine light from behind polarizers.
  2. Hold specimen between polarizers and apply stress at arrow.
  3. View photoelasticity effect through front desk.


Polarizing Karo

Demo: OP-H-PK
Pira Index: 6H 30.40

 Lab Equipment  Directions
  1.  Polarizing disks
  2. Karo syrup
  3. light source
  1.  Place the Karo syrup between the disks.
  2. Place the light source behind the disk and turn on.
  3. Rotate the front disk and watch the syrup change colors.
Note: This demo may be shown by laying polarizers on an overhead projector.


Polarization Equivalent

Demo: OP-H-PE
Pira Index: 6H 10.30

 Lab Equipment  Directions
  1.  2 refrigerator grates (wire shelves)
  2. rope
  1.  Insert the rope through the vertical bars of one grate and start a vertically oscillating wave along the rope behind the grate. Observe the transmission of the wave through the gate.
  2. Feed the rope through the second grate and align its bars in a horizontal direction. Again start the wave in the rope and observe whether it is transmitted through the grates.


Microwave Demo

Demo: OP-H-MD
Pira Index: 6H 10.20

 Lab Equipment  Directions
  1.  Microwave transmitter with pulg in cord and microwave receive mounted on board
  2. 4 metal gratings (2 round, 2 ‘square’)
Optional: Connect Fluke 8000 (set to DC volts and range 20) to receiver with 2 BB
  1.  Plug RCA end of cord into back of transmitter. (Red light should glow when plugged into wall).
  2. Turn sensitivity knob on receiver to low. Adjust intensity knob to 30x setting. Increase sensitivity knob as needed to obtain approximately a half-scale deflection.
  3. Insert square grating between transmitter and receiver with slits vertical. Then rotate grating 90 degrees.
  4. Insert second grating between first grating and transmitter at 0 degrees, 90 degrees, 45 degree angle to first.
  5. Use the round gratings to show the effect of slit size to wavelength ratio.


Flashlight and Glass Plate

Demo: OP-H-FG
Pira Index: 6H 20.10

 Lab Equipment  Directions
  1.  frame with glasses
  2. flashlight
  3. polarizer and holder (wood base)
  4. paper screen
  1.  Position the glass perpendicularly to the screen and shine the flashlight from the other end of the glass toward the screen.
  2. Angle the light so the beam strikes the glass, which transmits part of the light onto the screen. Notice that you see both the transmitted and reflected beams on the screen (photo #1).
  3. Rotate a polarizer in front of the flashlight so that the beam goes through it before hitting the glass. Notice that the reflected beam can be eliminated at certain positions of rotation.



Circular Polarizer

Demo: OP-H-CP
Pira Index: 6H 30.00

 Lab Equipment  Directions
  1.  Polaroid computer screen cover
  2. 2 square (approx. 6″) linear polarizers
  1.  Place the large circular polarizer on the OHP, “terminal side” upward, and focus the OHP.
  2. Light coming through the screen is circularly polarized. Slide a linear polarizer half way under the circular polarizer. Place 2nd linear polarizer on top of the screen polaroid and aligned with the first linear polarizer.
  3. Turn the top linear polarizer. Note that the light can be blocked by the linear polarizers, but not as it comes through the circular polarizer.