Acoustic Millikan Stopwatch Timers Millikan experiment with phyphox acoustic stopwatch: Millikan experiment was the first clear demonstration of the electric charge quantification and the determination of the elementary charge (charge of electron). Radius and charge of the oil drop in this experiment is determined from the two times: time 1 of the drop free fall over h = 1 mm and time 2 of its rise over the same height h under vertical electric field U/d, where U is electric tension applied between two metallic plates at distance d. The equations are given in the attached document. This version of the phyphox acoustic stopwatch as its prototype measures every time between two loud acoustic signals. These can be clicks, beeps, claps etc. as long as they are louder than the environment. You might want to adjust the threshold, giving the level at which the stop watch is triggered (ranging from 0 to 1). After starting the experiment, the clock will start measurement of time 1 on the first click exceeding the threshold and will be stopped on the second click. The third click will start measurement of time 2 and stop it on the fourth click. Two more clicks save the measured times and calculated radius and charge, and return the stopwatch to the original state. Make sure that the click is short enough as a long sound might be immediately detected as a stop. Mil green threshold mindelay recording rate i i2 t t2 limit max last tlist tlist1 ones tail dtlist tindex tcount tcount-1 t0 t1 t2 t3 t0effective t1effective t2effective t3effective tmax dt01 dt23 count index radius charge K U DT01 DT23 R Q threshold mindelay dt01 dt23 radius charge U recording count recording i max i index i2 i2 rate t max threshold t 0 t last tlist last last mindelay limit limit t t 0 t t 0 t tlist tlist dtlist 0 dtlist tlist tcount tcount 1 tcount-1 index count index index rate tmax t0 t1 t2 t3 0 1 tlist t0 1 1 tlist t1 2 1 tlist t2 3 1 tlist t3 t3 0 tmax t3 t3effective t2 0 tmax t2 t2effective t1 0 tmax t1 t1effective t0 0 tmax t0 t0effective t1effective t0effective dt01 t3effective t2effective dt23 dt01 radius dt01 dt23 K U charge tcount 6 dt01 DT01 tcount 6 dt23 DT23 tcount 6 radius R tcount 6 charge Q tcount 5 tlist tcount 5 0 index DT01 DT23 R Q