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: **
Prof. Smith - my resistor only has 4 colored bands; brown, green, brown, gold. I took this to be 150 ohm for the experiment.
** Initial voltage and resistance, table of voltage vs. clock time: **
4.0, 150
4.0, 0.00
3.5, 14.33
3.0, 31.17
2.5, 52.51
2.0, 80.81
1.5, 115.69
1.0, 166.98
0.75, 205.69
0.5, 259.42
0.3, 354.98
Voltage vs. clock time for resistor 150 ohm measured as capacitor was deenergized through a resistor.
** 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. **
80, 55, 87, 87
My graph is a very nearly inverse exponential relationship of voltage to clock time - decreasing at a decreasing rate
** Table of current vs. clock time using same resistor as before, again starting with 4 volts +- .02 volts. **
4.0, 150
30, 0
24, 30
20, 60
16, 90
14, 120
12, 150
10, 180
9, 210
8, 240
7, 270
6, 300
5, 330
4, 360
Current (A) vs. clock time for resistor 150 ohm measured as capacitor was deenergized through a resistor.
** Times to fall from initial current to half; 75% to half this; 50% to half this; 25% to half this, based on graph. **
115
135
135
135
Graph of current to clock time decreases at a decreasing rate - nearly inversely exponential.
** 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? **
No, No
The last 3 results for the current values were identical and the frist, third and fourth values of the voltage values were nearly identical but I see no pattern here.
** Table of voltage, current and resistance vs. clock time: **
25, 3.15, 24, 0.131
80, 2.05, 18, 0.114
158, 1.12, 12, 0.093
290, 0.40, 6, 0.067
424, 0.14, 3, 0.047
clock time, voltage, current (A), resistance
** Slope and vertical intercept of R vs. I graph; units of your slope and vertical intercept; equation of your straight line. **
.003, .04
R/I or ohms/A, ohms
R=.003A+.04
The graph increases at a steady rate - I used Excel to develop the equation
** Report for the 'other' resistor:; Resistance; half-life; explanation of half-life; equation of R vs. I; complete report. **
Left blank - short on time
** Number of times you had to reverse the cranking before you first saw a negative voltage, with 6.3 V .15 A bulb; descriptions. **
25
+-5
The bulb glowed very brightly upon reversal of cranking direction, probably as the capacitor was discharging at the same time the generator was adding to its discharge voltage. The voltage of the capacitor was reducing as the direction was reversed.
** When the voltage was changing most quickly, was the bulb at it brightest, at its dimmest, or somewhere in between? **
The bulb was brightest when the voltage was changing the quickest. As the voltage of the capacitor changes faster the bulb receives a greater voltage as well thus increasing its brightness
** Number of times you had to reverse the cranking before you first saw a negative voltage, with 33 ohm resistor; descriptions. **
3
Very accurate - I only had to reverse direction 3 times
The capacitor voltage reduced when the cranking direction was reversed thus discharging the capacitor in conjunction with the resistor's discharge
** 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. **
30, 20sec
Voltage change was greater over time closer to zero
3.163v peak
** Voltage at 1.5 cranks per second. **
~3.6v
** Values of t / (RC), e^(-; t / (RC) ), 1 - e^(- t / (RC)) and V_source * (1 - e^(- t / (RC) ). **
2.030, .0.009326, .0.9907, 3.566
** 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): **
3.566, 3.163
0.403, 11%
** According to the function V(t) = V_source * (1 - e^(- t / (RC) ), what should be the voltages after 25, 50 and 75 'beeps'? **
2.474, 3.248, 3.490
** Values of reversed voltage, V_previous and V1_0, t; value of V1(t). **
-3.6, 3.163, -6.763, 20
-1.925
** How many Coulombs does the capacitor store at 4 volts? **
16
F=C/V
C=FV=1.0*4=4
Q=CV=4*4=16
C stands for capacitance and Q for charge, then C = Q / V so that Q = C * V.
The units of C are Farads, the units of Q are Coulombs, so a Farad is a Coulomb / Volt (a Coulomb per volt).
** 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?; **
I need a little help here - I dont think my work in the previous box was correct as I keep coming up with V^2
** 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? **
See above
** 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? **
26.5A
** How long did it take you to complete the experiment? **
2000~2120 & 0730~0900 = 2:50
** **
A little confusion near the end, but excellent work. See my notes and let me know if you have questions.