PHY 2092 Section 4
Experiment 7: RC Circuit
Drew Walenty
Date Performed: 10/19/2022
Due: 10/26/2022
Lab Partner: Riley Wagner
GSA; Noufel Maalal
Introduction:
This lab always students to view how capacitors and resistors work with and against each other
in different ways. Students went through multiple procedures to view these things. In the first
part students constructed a series using a resistor and a capacitor. This allowed students to
measure the voltage changes that went along with time. In part 2 students made their own
capacitor from two small plates and a sheet of plastic. Finally students used an oscilloscope to
measure the time constant of different RC series circuits.
Data:
Part 1:
Time (s)
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
Volts (V)
ln(V)
5.06 1.62136648
4.6
1.5260563
4.3 1.45861502
4.07
1.403643
3.87 1.35325451
3.7 1.30833282
3.561
1.2700414
3.428
1.231977
3.3 1.19392247
3.204 1.16440003
3.093 1.12914149
2.985 1.09359975
2.89
1.0612565
2.806 1.03175998
2.715 0.99879195
2.644 0.97229292
2.568 0.94312739
2.492
0.9130856
2.427 0.88665593
2.362 0.85950872
100
105
110
115
120
125
130
2.303
2.247
2.19
2.132
2.089
2.036
2
0.83421262
0.80959599
0.78390154
0.75706051
0.73668548
0.7109871
0.69314718
Time Constant (theo) (Ohm*F)
120
Error in resistance (Ohm)
1.2
Error in Capacitance (F)
0.2
Error in Time Constant
24.02998127
Time Constant (Exp)
151.5151515
This is the time constants for part 1.
This table shows the voltage drops along with time of the series.
Part 2
Touching the capacitor rounds out the shark fin.
Insulating causes the curve to flatten a little.
Touching causes the wave to flatten completely.
Natural Log of Voltage Vs. Time
1,8
1,6
Voltage (ln(V))
1,4
1,2
1
0,8
0,6
0,4
y = -0,0066x + 1,4937
0,2
0
0
20
40
60
80
100
120
140
Time (s)
This is the natural log graph of voltage vs the time.
Part 3
increasing resistance increases the time constant and makes the fin smaller
increasing capacitance increases the time constant and makes the fin smaller
Trail
Resistance
Capacitance
Time Constant
Time Constant
(ohm)
(microF)
Capacitance (F) (Theo)
(Exp)
1
20,000
0.01
0.00000001
0.0002
0.00016
2
40,000
0.022
0.000000022
0.00088
0.00028
3
10,000
0.22
0.00000022
0.0022
0.00016
This tables shows the different trials from part three as well as the time constants.
d
Error in d
Capacitance Uncertainty
40
2
10%
600
2 Resistance Uncertainty
2040
2
1%
This tables shoes the values of the errors in the experiment.
This is the graph for trial one.
This is the graph for trial two.
This is the graph for trial 3.
Data Analysis:
T=RC
Time constant= 20000*0.00000001= .0002
Discussion:
The physics of the experiment is viewed all through an RC circuit. An RC circuit is a series that
contains a resistor and a capacitor. This circuit is what the whole lab was based off of because it
allowed students to view how these circuits acted with different amount of resistance and
capacitance in them.
This lab didn’t have any major errors the main error would be human error when students timed
the voltage drops. You can’t get perfectly accurate results due to just trying to look at the times
on the videos.
The largest experimental error in the first part of the experiment is when students had to use a
video to time how long it took the series to drop to 2.0 volts. The difference in the Vc and Vr is
due to the order of the resistor and capacitor. When the resistor is first it starts low and rises
through the capacitor. When they are switched the graph starts high through the capacitor and
drops through the resistor.
Conclusion:
In conclusion this experiment was another success as students were able to see how these RC
circuits work and what causes certain changes. We also saw how these circuits held voltage
when disconnected from power. We had minimal errors, and this experiment was another
success. My lab partner Riley was a big help as we worked very well together.