Category Archives: Color

Tri-Color LED

Demo: OP-F-TL
Pira Index: 6F 10.36

 Lab Equipment  Directions
  1.  Tri-color LED box
  1.  Push each button in turn to show the 3 colors (RGB) that light up the plexiglass triangle.
  2. Push each combination of 2 colors to see the resulting color (CMY).
  3. Push all 3 buttons at the same time to show the resulting white light from adding RGB.



Slit and Slat Spectra

Demo: OP-F-SS
Pira Index: 6F 10.26

 Lab Equipment  Directions
  1.  File folder with slit
  2. ruler-plastic slat
  3. 4″x4″ holographic grating in frame with stoppers for support
  4. overhead projector
  1.  Place the grating in front of the lends on the OHP.
  2. Place the file folder near the back of the platform with the slit running lengthwise on the OHP.
  3. Place the ruler in line with the slit, but at the front of the OHP platform.
  4. Observe and compare the upper spectra (RGB) and lower subtractive colors (CMY) seen on the projection screen.



Sunset Effect, OHP

Demo: OP-F-SO
Pira Index: 6F 40.00

 Lab Equipment  Directions
  1.  1000ml beaker
  2. photo fixer solution – 6g per 800mL water
  3. bottle of 6M sulfuric acide (caution)
  4. overhead mask (file folder) with cut outs
  5. eye dropper
  6. stirring rod
  7. large polarizer
  8. overhead projector
approximately 4 min demo at 72 degrees
  1.  Place the mask and cut outs on the overhead.
  2. Pour the photo fixer into the beaker and place the beaker over the hole in the mask.
  3. Fill the eye dropper (~3ml) with acid and acid drop by drop while stirring. ‘Watch the sun go down’
  4. Use polarizer to show scattered light is polarized.



Sunset Effect

Demo: OP-F-SE
Pira Index: 6F 40.10

 Lab Equipment  Directions
  1.  small flood lamp
  2. large tank of water
  3. creamer
  1.  Add a small pinch of creamer to the tank of water.
  2. Shine the light into the tank.
  3. Light scatters into different colors like the sunset. Side view is blue but red is emitted on the other side.



Strobe Disk

Demo: OP-F-SD
Pira Index: 6F 10.25

 Lab Equipment  Directions
  1.  strobotac
  2. 12 in 1 apparatus
  3. color wheel
  1.  Turn on color wheel.
  2. Turn on strobotac and set as specified.



Glass Filter Absorption

Demo: OP-F-GF
Pira Index: 6F 10.55

 Lab Equipment  Directions
  1.  Glass blower’s glasses
  2. file folder with slit
  3. 4″ x 4″ holographic grating in frame with stopper for support
  4. small piece fluorescent pink plastic
  5. overhead projector
  1.  Lay the folder onto the overhead with the slit near the middle and focus the slit on the screen.
  2. Place the star grating over the top/front lens of the overhead projector as shown.
  3. You will see a continuous spectrum.
  4. Lay one side of the glasses across the slit as shown. Notice that the glasses absorb the yellow  band, resulting in a dark line at that position in the spectrum. (Didymium glass absorbs the sodium spectra).
  5. Repeat with the piece of plastic in place of glasses.



Color Absorption, OHP

Demo: OP-F-CO
Pira Index: 6F 10.20

 Lab Equipment  Directions
  1.  3 colored filters attached to folder
  2. overhead projector
  3. 4″ x 4″ holographic grating in frame with stoppers for support
  4. laser pointer
  1.  Place the folder onto the overhead.
  2. Holding the star grating at an angle to the overhead lamp, look at the spectra of each of the filters. Using the laser pointer, point ou the area of the missing blue and green bands corresponding to the red filter, and so one with the other two filters.



Color Mixing

Demo: OP-F-CM
Pira Index: 6F 10.10

 Lab Equipment  Directions
  1.  Three colored lights (blue, red, green)
  2. screen or wall
  3. plug strip
  1.  Turn on lights and aim the beams at the same spot on the wall or screen. You should see white light resulting from the combination of three lights.
  2. If light is not quite white, adjust each light intensity or vary the distance of the individual lights from the screen.
  3. Put your hand, meter stick, or some object in white light area and observe colored shadows. Each shadow is composed of two primaries. For example, if red is blocked the shadow is a combination of blue and green.



Color Disk

Demo: OP-F-CD
Pira Index: 6F 10.25

 Lab Equipment  Directions
  1.  Variable speed rotator
  2. color disk
  1.  Clamp the color disk onto the collet of the variable speed rotator.
  2. The spindle of the rotator should be clamped in such a position that the plane of the disk is vertical



Color Absorption Filament

Demo: OP-F-CA
Pira Index: 6F 10.20

 Lab Equipment  Directions
  1.  bulb with 3 colored filters around it
  2. diffraction gratings
  3. variac
  1.  Turn on the bulb and look at the bright white strips of lights through a grating.
  2. There are 3 darker strips interspersed between the bright ones. Comparing the first darker strip (red filter) with a bright one, you should see only red part of the spectrum, blue and green are missing. The next dark strip (blue filter) will show only blue, missing red and green parts, and likewise for the green.