phy 122
Your 'the rc circuit' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.
** Your comment or question: **
** Initial voltage and resistance, table of voltage vs. clock time: **
4v,100 ;3.5v,5sec;3.0v,11sec
2v,20sec;1.5v,26sec;1v,32sec;.75v,38sec;.5v,40s;.25v,42s
** Times to fall from 4 v to 2 v; 3 v to 1.5 v; 2 v to 1 v; 1 v to .5 v, based on graph. **
.20s
.14s
.12s
.6s
as voltage decreases time increase
** Table of current vs. clock time using same resistor as before, again starting with 4 volts +- .02 volts. **
5s,80ma;10s,70ma;15s,60ma;20s,55ma;25s,45ma;30s35ma;35s30ma;40s25ma
i saw ma decrease as a function of time
** Times to fall from initial current to half; 75% to half this; 50% to half this; 25% to half this, based on graph. **
28s
14s
5s
7s
the graph shows the drop in mamps vs. time
** Within experimental uncertainty, are the times you reported above the same?; Are they the same as the times you reports for voltages to drop from 4 v to 2 v, 3 v to 1.5 v, etc?; Is there any pattern here? **
yes very close
close
yes the circuit lost both voltage and mamps
** Table of voltage, current and resistance vs. clock time: **
i used v=ir
4v,8a,5m,0s
2.6v,.6a,4.3m,14s
2v,.4a,5m,20s
.1v,.2a,.05m,42s
.05v,.1a,.5m,48s
** Slope and vertical intercept of R vs. I graph; units of your slope and vertical intercept; equation of your straight line. **
.28,.09
amps/ohms,amps
i=.28r+.09
the slope was the difference in amps2-amps1
** Report for the 'other' resistor:; Resistance; half-life; explanation of half-life; equation of R vs. I; complete report. **
33ohms
7sec+-.6sec
i made 3 timed runs
** Number of times you had to reverse the cranking before you first saw a negative voltage, with 6.3 V .15 A bulb; descriptions. **
4
yes within 2
when changing direction bulb goes out for a instances
** When the voltage was changing most quickly, was the bulb at it brightest, at its dimmest, or somewhere in between? **
dimmest
as capacitor voltage drops the bulb gets dimmer
** Number of times you had to reverse the cranking before you first saw a negative voltage, with 33 ohm resistor; descriptions. **
5 time
yes
i cranked the to 15ma and then began the reversing
** How many 'beeps', and how many seconds, were required to return to 0 voltage after reversal;; was voltage changing more quickly as you approached the 'peak' voltage or as you approached 0 voltage; 'peak' voltage. **
61 beebs, 31 seconds
voltage changed quicker approaching zero
5 volt
** Voltage at 1.5 cranks per second. **
.4 volt
** Values of t / (RC), e^(-; t / (RC) ), 1 - e^(- t / (RC)) and V_source * (1 - e^(- t / (RC) ). **
1.8=t
.054
.946
3.9volts
** Your reported value of V(t) = V_source * (1 - e^(- t / (RC) ) and of the voltage observed after 100 'cranks'; difference between your observations and the value of V(t) as a percent of the value of V(t): **
3.9v
97%
** According to the function V(t) = V_source * (1 - e^(- t / (RC) ), what should be the voltages after 25, 50 and 75 'beeps'? **
2.9v
1.95v
.95v
** Values of reversed voltage, V_previous and V1_0, t; value of V1(t). **
-4v,1.6v0v31s
3v
v1(t)=vprev+0
** How many Coulombs does the capacitor store at 4 volts? **
16c
** How many Coulombs does the capacitor contain at 3.5 volts?; How many Coulombs does it therefore lose between 4 volts and 3.5 volts?; **
4.5c,.5c
** According to your data, how long did it take for this to occur when the flow was through a 33-ohm resistor?; On the average how many Coulombs therefore flowed per second as the capacitor discharged from 4 V to 3.5 V? **
.7s,1.75c/s
** According to your data, what was the average current as the voltage dropped from 4 V to 3.5 V?; How does this compare with the preceding result, how should it compare and why? **
.7amps
its close
** How long did it take you to complete the experiment? **
6 hours
** **
Your work on this lab looks very good.