Lab03_B
pdf
keyboard_arrow_up
School
University of Virginia *
*We aren’t endorsed by this school
Course
1429
Subject
Electrical Engineering
Date
Apr 3, 2024
Type
Pages
8
Uploaded by MajorFangPartridge16
Lab 3 Capacitors
L3-1
Name
Date
Partners
Lab 3 - B - A Breath of Fresh... Water?
OBJECTIVES
After successfully completing this laboratory, you should be able to:
•
understand the parameters that determine the capacitance of a given capacitor,
•
describe the behavior of capacitors in DC circuits, and
•
discuss various methods of determining the capacitance of an unknown capacitor.
Recommended Reading:
Walker 20.5-20.6, 21.6; Giancoli 24.1-24.3, 26.5; Knight 21.4-21.8,
23.5-23.7; OpenStax 19.5-19.7, 21.6
EQUIPMENT
For your preliminary investigation, you will use a large blue capacitor (x2), light bulb #133,
alligator clips (x2), and a double throw switch. For your RC investigation, you will use a 47
µ
F capacitor (white plug) and 10 k
Ω
resistor (brown plug). You will also use a PASCO voltage
supply, connecting wires (x5), a voltage probe, and a multimeter. There will also be two PASCO
RLC boards per room available for observation.
PROBLEM
You have been studying pulmonary edema, a condition that causes an excess of fluid to accu-
mulate in the lungs, and are hoping to better understand some of the diagnosis techniques. Your
research thus far has revealed that one possible technique involves monitoring the capacitance
of the lungs, which changes with the addition of fluid.
You hope to improve your understanding of the behavior of capacitors, and based on this under-
standing develop a straightforward method of extracting information about the percentage of a
lung that has become filled with fluid.
University of Virginia Physics Department
PHYS 2040
/
2419, Spring 2024
L3-2
Lab 3 Capacitors
DISCUSSION AND EXPLORATION
Question 1:
Consider the circuit below, where the capacitor is initially uncharged:
Explain qualitatively what you expect will happen in the following situations:
1. the switch is first in position 2,
2. the switch is moved to position 1, and
3. the switch is moved back to position 2.
Be specific about the physical processes happening in each element of the circuit.
Use the additional box below if you need it.
University of Virginia Physics Department
PHYS 2040
/
2419, Spring 2024
Lab 3 Capacitors
L3-3
Question 2:
Sketch a prediction for the voltage across the capacitor as a function of time
when the switch is moved into position 1 after being in position 2 for a long time
.
Provide a physical explanation for the shape of your graph. Be specific about the shape.
Sketch:
University of Virginia Physics Department
PHYS 2040
/
2419, Spring 2024
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
- Access to all documents
- Unlimited textbook solutions
- 24/7 expert homework help
L3-4
Lab 3 Capacitors
Question 3:
Sketch a prediction for the voltage across the capacitor as a function of time
while the switch is moved into position 2 after being in position 1 for a long time
.
Provide a physical explanation for the shape of your graph. Be specific about the shape.
Sketch:
In your exploration questions below use the PASCO power supply set at 6 V DC instead
of a battery pack shown in the video. Make sure to use the large cylindrical capacitor
(large blue capacitor) to answer Q4 and 5.
University of Virginia Physics Department
PHYS 2040
/
2419, Spring 2024
Lab 3 Capacitors
L3-5
Question 4:
To check your predictions about the behavior of the light bulb assemble the
circuit from question
1. To get help you with this circuit watch the first video in your
in-lab 3B assignment on WebAssign. Once you built your own circuit observe the behavior
of the light bulb. How do your predictions and results compare? Explain.
Question 5:
To test your predictions about the shape of the Voltage vs. Time graphs we
can connect the voltage probe across the capacitor and take the necessary measurements.
Watch how the measurement is done in the second video on WebAssign. Assemble your
own circuit and collect the data. How do your predictions and results compare? Explain
any discrepancies. For your future reference upload graphs into your in-class assignment.
University of Virginia Physics Department
PHYS 2040
/
2419, Spring 2024
L3-6
Lab 3 Capacitors
Question 6:
It is convenient to discuss capacitor charging
/
discharging time in terms of
a time constant – that is, the time required for the capacitor to reach about 63% of its
maximum charge capacity:
τ
=
RC
(3.1)
Use this expression to devise a method to indirectly measure the capacitance of an unknown
capacitor. Explain.
Hint: How is the charge on a capacitor related to the voltage across
the capacitor? How can you determine the time it takes to get to 63% of the total possible
charge from a voltage vs. time graph?
Question 7:
To test your predictions we can construct the following circuit with a 10 k
Ω
resistor and a nominal 47
µ
F capacitor mounted on a white plug. Watch the third video in
your in-lab 3B assignment on WebAssign to see how this measurement can be done.
University of Virginia Physics Department
PHYS 2040
/
2419, Spring 2024
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
- Access to all documents
- Unlimited textbook solutions
- 24/7 expert homework help
Lab 3 Capacitors
L3-7
Question 8:
Using the method devised in Question 6 conduct your own measurement and
analyze the data to determine the capacitance. Compare the results of your method with the
results of measuring the capacitance with a multimeter. Calculate the uncertainties on your
final values and show the details below. How well do the values agree? Explain. Upload
any relevant graphs into your in-class assignment. Record your values in the appropriate
spaces below.
Capacitance measured from time
=
±
µ
F
Capacitance measured with multimeter
=
±
µ
F
Ask your class instructor about the error of measurements made with the multime-
ter.
Concept Check
Consider the following circuit, in which a light bulb (indicated by the circle with an
X
through
it) and two capacitors are connected to a battery in series.
University of Virginia Physics Department
PHYS 2040
/
2419, Spring 2024
L3-8
Lab 3 Capacitors
Question 9:
Respond to each of the following student predictions of how the circuit will
behave. Be sure to indicate which student, if any, you agree with and why.
1. We predict that the light bulb will never light up because it is e
ff
ectively disconnected
from the DC power supply at both ends by the two capacitors.
The empty space
between capacitor plates prevents a current from flowing in the circuit.
2. We predict that the light bulb will light up when the DC power supply is turned on
and remain lit. We saw before that when there is one capacitor, it will charge fully
and block the flow of current. However, now there are two capacitors so each will
only charge half as much and won’t block the current.
3. We predict that the light bulb will light up when the DC power supply is turned on
and dim as before. However, when the power supply is turned o
ff
the two currents
from the discharging capacitors will cancel each other and the bulb will not light up.
If you are having trouble thinking about these questions, watch the last video in your in-lab 3B
assignment on WebAssign to see the circuit in action.
Be prepared to discuss with the class.
Please clean up your lab area
University of Virginia Physics Department
PHYS 2040
/
2419, Spring 2024
Related Documents
Related Questions
91)Give
Short Ansaers:-
a) Determine the dimensions of
and Inductance.
2) Differentiiate
classi Fication used
c) Difine
resoluticn one
Capacitance
between different
for
Absolute
standards
Electrical measurinents
accuracys
and
elror
example each,
arrow_forward
Give a description of capacitive reactance and back up your description with examples/evidence.
arrow_forward
12
arrow_forward
What are very rough estimates of the graphs of capacitor voltage vs. time and resistor voltage vs. time while charging and discharging?
arrow_forward
Fill in the blanksadd, capacitance, charge capacity, dielectric, dissipate, electrical circuits, , passive, plates,proximity, storesA capacitor is a 1 …………. two-terminal electrical component that 2 ……… potential energy in anelectric field. The effect of a capacitor is known as 3. …………... While some capacitance exists betweenany two electrical conductors in 4. …………… in a circuit, a capacitor is a component designed to 5.…… capacitance to a circuit. The capacitor was originally known as a condenser.The physical form and construction of practical capacitors vary widely and many capacitor types are incommon use. Most capacitors contain at least two electrical conductors often in the form of metallic 6.………… or surfaces separated by a 7. ………medium. A conductor may be a foil, thin film, or anelectrolyte. The nonconducting dielectric acts to increase the capacitor's 8. ………… ………. Materialscommonly used as dielectrics include glass, ceramic, plastic film, paper, mica, and oxide…
arrow_forward
What is the equation thst represents the relationship between charge, capacitance and voltage for a capacitor.
arrow_forward
In the first method to write the equation, why is the capacitor value not included in the equation at first?
arrow_forward
Please solve this
arrow_forward
SEE MORE QUESTIONS
Recommended textbooks for you
Delmar's Standard Textbook Of Electricity
Electrical Engineering
ISBN:9781337900348
Author:Stephen L. Herman
Publisher:Cengage Learning
Related Questions
- 91)Give Short Ansaers:- a) Determine the dimensions of and Inductance. 2) Differentiiate classi Fication used c) Difine resoluticn one Capacitance between different for Absolute standards Electrical measurinents accuracys and elror example each,arrow_forwardGive a description of capacitive reactance and back up your description with examples/evidence.arrow_forward12arrow_forward
- What are very rough estimates of the graphs of capacitor voltage vs. time and resistor voltage vs. time while charging and discharging?arrow_forwardFill in the blanksadd, capacitance, charge capacity, dielectric, dissipate, electrical circuits, , passive, plates,proximity, storesA capacitor is a 1 …………. two-terminal electrical component that 2 ……… potential energy in anelectric field. The effect of a capacitor is known as 3. …………... While some capacitance exists betweenany two electrical conductors in 4. …………… in a circuit, a capacitor is a component designed to 5.…… capacitance to a circuit. The capacitor was originally known as a condenser.The physical form and construction of practical capacitors vary widely and many capacitor types are incommon use. Most capacitors contain at least two electrical conductors often in the form of metallic 6.………… or surfaces separated by a 7. ………medium. A conductor may be a foil, thin film, or anelectrolyte. The nonconducting dielectric acts to increase the capacitor's 8. ………… ………. Materialscommonly used as dielectrics include glass, ceramic, plastic film, paper, mica, and oxide…arrow_forwardWhat is the equation thst represents the relationship between charge, capacitance and voltage for a capacitor.arrow_forward
arrow_back_ios
arrow_forward_ios
Recommended textbooks for you
- Delmar's Standard Textbook Of ElectricityElectrical EngineeringISBN:9781337900348Author:Stephen L. HermanPublisher:Cengage Learning
Delmar's Standard Textbook Of Electricity
Electrical Engineering
ISBN:9781337900348
Author:Stephen L. Herman
Publisher:Cengage Learning