INSTRUCTIONS ON DRIPPING FAUCET LAB:

 

1) OPEN THE PROGRAM ULI TIMER THAT CAN BE FOUND IN THE ULI FOLDER ON THE APPLE MENU.

 

2) CHECK THAT THE PHOTOGATE SYSTEM (METAL BRACKET WITH EMITER & DETECTOR ON EACH SIDE) WORKS BY INTERPOSING YOUR HAND ON THE BEAM AND NOTICING IF THE TOP LEFT INDICATOR ( [_] SHAPE) CHANGES FROM OPEN TO BLOCKED. IF IT DOES NOT, CHECK THAT THE ULI BOX IS TURNED ON, AND THAT THE CABLE COMING FROM THE PHOTOGATE SYSTEM IS CONNECTED TO THE DATA IN PORT IN THE ULI BOX.

 

3) OPEN FROM THE WINDOWS MENU A "NEW GRAPH" WINDOW TO MONITOR THE BEAM INTERRUPTIONS.

 

4) CLICK THE START BUTTON ON THE TOP THE SCREEN TO START COLLECTING DATA (BEAM INTERRUPTIONS WITH YOUR HAND).

 

5) ONCE YOU ARE FAMILIAR WITH THE OPERATION, CAREFULLY PLACE THE PHOTOGATE SYSTEM ON TOP THE TABLE IN SUCH A WAY THAT FALLING DROPS WILL INTERRUPT THE BEAM. THIS ALIGNMENT IS VERY CRITICAL FOR THE SUCCESS OF THE EXPERIMENT! A DROP RATE OF ABOUT 1 DROP PER SECOND SHOULD WORK TO HELP YOU "FINE TUNE" THE ALIGNMENT. YOU SHOULD SEE ONE DOT IN THE GRAPH SCREEN EVERY TIME YOU HEAR A DROP SPLASH...

 

6) THE BEST WAY TO DISPLAY YOUR DATA IS BY GRAPHING NOT "Dt1" VERSUS TIME ELAPSED, BUT ITS RECIPROCAL (1/Dt1= THE DRIPPING FREQUENCY) VERSUS TIME ELAPSED. TO DO THAT, YOU WILL NEED TO GO TO THE DATA MENU, SELECT NEW FORMULA. THE SETUP WINDOW WILL APPEAR AND YOU CAN RENAME IT "FREQUENCY" ON THE LINE NEXT TO f(x).

NEXT TO THE FOLLOWING LINE (= SIGN) TYPE: 1/"Dt1"

Dt1 stands for "greek delta"t1, and is obtained by typing OPTION-j, or by copying and pasting the symbol from the previous formula.

THE THIRD LINE (UNITS) YOU CAN TYPE 1/s.

 

7) GO TO THE GRAPH WINDOW AND CHANGE THE VERTICAL AXIS LABEL BY CLICKING ON IT AND SELECTING THE NEW 1/Dt1 VARIABLE YOU JUST CREATED.

 

8) YOU ARE NOW READY TO TAKE DATA. START WITH A SLOW DRIPPING RATE AND GRADUALLY INCREASE IT WHILE RECORDING WITH THE ULI THE DRIPPING FREQUENCY. AFTER A FEW TRIAL RUNS, YOU SHOULD BE ABLE TO FINE TUNE THE DRIPPING RATE TO SEE PERIOD DOUBLING BIFURCATIONS (PERIOD 2, 4 AND 8 AT LEAST). TRY TO ESTIMATE FROM THIS DATA THE VALUE OF THE FEIGENBAUM NUMBER (DELTA=4.669....).

 

9) SAVE THE FILES WITH THE "NICEST" DATA FOR FURTHER STUDIES OF THE DOUBLING CASCADE AND THE ATTRACTORS. PRINT YOUR GRAPHS.

 

10) YOU CAN EXPAND THE STUDY (INFLUENCE OF DROP SIZE) IF YOU WISH BY ATTACHING NEEDLES OF DIFFERENT DIAMETERS TO THE PLASTIC NOZZLE (WHICH ACTUALLY IS THE END OF A SYRINGE), BUT BE VERY CAREFUL WITH THEIR SHARP TIPS. IN THE UNLIKELY CASE YOU PUNCTURE YOURSELF WITH A NEEDLE, PLEASE MAKE SURE TO REMOVING IT IMMEDIATELY FROM THE NOZZLE, PLACING IT IN THE PROTECTIVE PLASTIC ENCLOSURE, AND GIVING IT TO THE INSTRUCTOR FOR PROPER DISPOSAL. GET ADEQUATE CARE OF THE CUT WITH DESINFECTANTS.