Category Archives: Modern Physics

Relativistic Effects Current Swing

Demo: MP-F-CS
Pira Index: 7F 00.00

 Lab Equipment  Directions
  1.  Current swing foil apparatus
  2. Edison 7 volt battery
  3. 2 AA long leads
  4. overhead projector
  1.  Connect the negative terminal lead to the foil square marked negative.
  2. Touch the positive terminal lead to square ‘A’, marked positive (current goes the opposite direction through each strip). The two adjacent foils repel each other.
  3. Touch the positive terminal lead to square ‘B’, the other positive square (current goes the same direction through both strips). The two adjacent foils attract each other.


Radiation Sand

Demo: MP-D-RS
Pira Index: 7D 10.10

 Lab Equipment  Directions
  1.  Eight bottles (which contain various masses of sand representing radiation dosages for specified environments)
  1.  Makes a comparison of the amounts of radiation received from various activities and environments.



Demo: MP-D-RA
Pira Index: 7D 10.10

 Lab Equipment  Directions
  1.  Geiger counter
  2. Gamma source set
  3. Various other radioactive sources
  1.  Turn on the counter and place sample under Geiger tube.
  2. Test to see how distance from the sample affects the count.
  3. Place paper, wood, lead, and other items between the source and the tube to check their shielding properties.


Half-Life Nuclear Decay

Demo: MP-D-HL
Pira Index: 7D 10.00

 Lab Equipment  Directions
  1.  64 ping pong balls
  2. board with clothespin triggers
  3. large darkroom clock
  4. 4 C-clamp (to hold down boards)
  1.  With the clothespins locked, release at random 32 balls in a set length of time.
  2. Repeat, releasing 16 balls, then 8 balls, then 4 balls, then 2 balls, with each group being released over the same set length of time.


Half-Life Decay, BA-137

Demo: MP-D-HB
Pira Index: 7D 10.20

 Lab Equipment  Directions
  1.  Thornton counter
  2. Geiger tube with stand
  3. Barium ‘cow’ (minigenerator)
  4. half-life eluant solution
  5. planchet
  6. stopwatch
  1.  Set up as shown connecting the Geiger tube to 450V and input terminals.
  2. Squeeze 2-3 drops of eluant through Barium cow (may need to discard first 2 drops) onto a planchet.
  3. Place planchet under the Geiger tube.
  4. Use the stopwatch to time the number of counts for equal time intervals.


Cloud Chamber

Demo: MP-D-CC
Pira Index: 7D 30.60

 Lab Equipment  Directions
  1.  Cloud chamber apparatus
  2. Funnel and squirt bottle
  3. Ethanol 90% (1 liter)
  4. anti-fog solution and cloth
  5. black elastic ‘skirt’
  6. Big Foot door stops
  7. 35mm projector
  8. telescope book (for height adjustment)
  9. gamma source kit (optional)
  10. dry ice – to make, need: carbon dioxide tank, dry ice machine
  1.  Rub all inside surfaces of chamber and lid with anti-fog solution.
  2. Place black ‘skirt’ around lower outside perimeter of base. Remove top chamber and cover base with chunks of dry ice.
  3. Set chamber on top of dry ice and use door stops as shims to make chamber level.
  4. Soak all felt pads inside chamber with alcohol and pour remaining alcohol and pour remaining alcohol into chamber.
  5. Align projector so that light shines just across alcohol surface.
  6. As apparatus cools down you should see tracks of environmental radioactivity or a gamma disk can be placed on shelf in chamber.


Transmission and Absorption

Demo: MP-B-TA
Pira Index: 7B 11.00

 Lab Equipment  Directions
  1.  Pasco blazed diffraction grating
  2. 4 slit slides with cuvettes
  3. prism lab stand
  4. 90 degree clamp
  5. slide projector
  1.  Place the clear cuvette slide into the slide projector. Set the stand with the diffraction grating in front of the projector. You will see 2 complete spectra on the screen (one above the other).
  2. Remove the clear slide and replace with the red filter cuvette. Notice that only the red part of the spectra comes through on the bottom spectra.
  3. Repeat with the blue and green filters.