Physics 101 Activity #8: Virtual Capacitance

This lab uses the Capacitance simulation from PhET Interactive Simulations at University of
Colorado Boulder, under the CC-BY 4.0 license.
Construct the following electrical circuit (Capacitor), using PhET simulation, or
using the following link.

https://phet.colorado.edu/en/simulation/legacy/capacitor-lab

Today we will be exploring the energy stored in a capacitor, behavior of capacitors with and without
dielectrics, and the capacitor connection (series and parallel). You will complete the virtual lab using the
Capacitor Lab from Phet, data analysis software (Excel) and this document. Each member of the lab
group must complete this important assignment.

Department of applied Physics and Astronomy Capacitors Bassam Rashed

 First part
Energy stored in the capacitor versus Voltage
1- Open the (https://phet.colorado.edu/en/simulation/capacitor-lab)
2- Set the plates to the minimum area (400.0 mm2), maximum separation (5.0 mm) and maximum
3- Using the provided meters ( charge, energy, Electric field E, and voltmeter) in the simulation
complete the following data table
εo A
4- Calculate the capacitance using Co = , this the real value.
d
5- Increase the voltage from the battery and record the values of the voltage across the capacitor(V),
Charge on the plate(q), and energy stored (EPE)

εo A
Separation d (__________ m) Plate Area A (__________ m2) Capacitance Co = (__________F)
d
Trial Potential Charge Q Stored Electric Field V2 ( volt)2 q2 (C2) E2(V/m)2
difference V (C) Energy EPE between plates E
(V) (J) (V/m)

10

6- Use Excel to plot the relationship between (V2, U), using V2 in the most left column in Excel.
1
7- Use the equation U = CV 2 , to determine C0 using the slope of the graph.
2
8- Compare this value of C0 with C0 in the table. Calculate the percentage error.

9- Attach the graph to your data report.

10- Use Excel to plot the relationship between (q2, U), using q2 in the most left column in Excel.

Department of applied Physics and Astronomy Capacitors Bassam Rashed

 Q2
11- Use the equation U = , to determine C0 using the slope of the graph.
2C
12- Compare this value of C0 with C0 in the table. Calculate the percentage error.

13- Attach the graph to your data report.

1
14- Use the equation u = ε o E 2 , to determine ε o using the slope of the graph.
2
15- Compare this value of ε o with ε o =8.85x10-12 F/m. Calculate the percentage error.

Second part
Dielectrics and Capacitance
1- Open the (https://phet.colorado.edu/en/simulation/capacitor-lab)
2- Click on the “Dielectrics” tab.
3- Set the plates to the area A between (195- 205 mm2), separation d between (7.5- 8.5 mm),
maximum positive battery voltage (1.5 V) and minimum dielectric constant (1) with zero offset to
begin. See fig. below.

εo A
4- Determine the value of Co = and compare it to the value from the par chart.
d

Department of applied Physics and Astronomy Capacitors Bassam Rashed

 5- Insert the dielectric material in the capacitor, and determine the value of the capacitance C (in
F)

6- Change the value of the dielectric constant K then complete the following data table (keep the
plate separation and area constant through all trials)

C0 = F

Dielectric Constant Capacitance (F)

Trial
K C

1 1

2 1.5

3 2

4 2.5

5 3

6 3.5

7 4

8 4.5

9 5

7- Draw the best fit using Excel between (K, C), and find the slope of the line.
8- Attach the graph to your lab report.
9- Use the equation C = KCo , determine C0 and compare it to the value.

10- Calculate the percentage error in C0.

Department of applied Physics and Astronomy Capacitors Bassam Rashed

 Third part
Dielectrics and Capacitance (Battery Connected)

1- Open the (https://phet.colorado.edu/en/simulation/capacitor-lab)

2- Click on the “Dielectrics” tab.
3- Set the plates to the area A between (195- 205 mm2), separation d between (7.5- 8.5 mm),
maximum positive battery voltage (1.5 V) and minimum dielectric constant (1) with zero offset
to begin.
4- Using the provided meters (charge, energy, Electric field E, and voltmeter) in the simulation
complete the following data table

Department of applied Physics and Astronomy Capacitors Bassam Rashed

 5- In the table below record the values of Capacitance C0, Electric field E0, stored energy U0, and
charge on p late Q0 and potential difference V0.
6- Slide the dielectric inside the capacitor and record the values shown in the table below.

C0 =_______ F , E0 =_______ V/m, q0 = _________C, EPE0 =_______J, V0 =_______V

Trial Dielectric Capacitance Stored Plate Electric Field Electric Field Sum Electric V ( Volt)
Constant C (F) Energy Charge q between the in Dielectric Field
(C) plates E0 Ei (V/m) between
K EPE (J)
(V/m) E (V/m)

1 1

2 1.5

3 2

4 2.5

5 3

6 3.5

7 4

8 4.5

9 5

7- Analyze the data above and answer the following questions. You may want to create graphs to
better explain relationships between variables. Attach any graphs or figures you create with the
data to explain your responses.

8- How does the dielectric constant affect capacitance?

9- As the dielectric constant increases, how does the total stored energy change?

10- Does the dielectric constant affect the amount of charge stored on the plate? If so, what is the
relationship?

Department of applied Physics and Astronomy Capacitors Bassam Rashed

 Fourth part
Dielectrics and Capacitance (Battery Connected)

1- Open the (https://phet.colorado.edu/en/simulation/capacitor-lab)

2- Click on the “Dielectrics” tab.
3- Set the plates to the area A between (195- 205 mm2), separation d between (7.5- 8.5 mm),
maximum positive battery voltage (1.5 V)
4- Using the provided meters (charge, energy, Electric field E, and voltmeter) in the simulation
complete the following data table

11- In the table below record the values of Capacitance C0, Electric field E0, stored energy U0, and
charge on p late Q0 and potential difference V0.

Department of applied Physics and Astronomy Capacitors Bassam Rashed

 5- Disconnect the battery from the capacitor.

6- Select the material of dielectric constant to be paper (K= 3.5), slide it inside the capacitor, then
record the values of the quantities in the table below

K= 3.5 (paper) q(pC) C (pF) V(V) E(V/m) EPE (J)

Connected Battery
without Dielectric
Disconnected Battery
with dielectric

7- Use the formulas to check and comment on your results. Where q, C, V, E, and EPE with
dielectric and C0, E0, EPE0, q0 and V0 without dielectric.
Vo U E
Q = ? Qo , C = KCo , V = ,U = o , E = o
K K K
8- Comment on your results.

Department of applied Physics and Astronomy Capacitors Bassam Rashed

 Fifth part
Series Connection
1- Open the (https://phet.colorado.edu/en/simulation/capacitor-lab)
2- Click on the “Multiple Capacitors” tab.
3- Click on three capacitor in series button.
4- Move the voltage slide to maximum and measure the voltage across the battery with the
voltmeter Vmax=………………………..V,click on three capacitors in series
5- Change the settings on the 3 capacitors to : C1= 1pF, C2= 2pF, C3= 2.5pF , as shown below

6- Now measure the voltage across each capacitor. V1= ______ V2=_____ V3=____

7- What is the relationship of voltages?

8- Using the stated capacitance (1.0x10-13 F, 2.0x10-13 F, 2.5x10-13 F) find the charge on each

capacitor. q1=____ q2=____ q3=____

9- Comment on your results of the stored charge with q1, q2, and q3.

Department of applied Physics and Astronomy Capacitors Bassam Rashed

 10- What is the total capacitance in Farads? Read meter.

11- Use formula to find the total capacitance

Sixth part
Parallel Connection
1- Open the (https://phet.colorado.edu/en/simulation/capacitor-lab)
2- Click on the “Multiple Capacitors” tab.
3- Click on three capacitor in series button.
4- Move the voltage slide to maximum and measure the voltage across the battery with the
voltmeter Vmax=………………………..V . click on three capacitors in parallel.
5- Change the settings on the 3 capacitors to : C1= 1pF, C2= 2pF, C3= 2.5pF , as shown below

6- Now measure the voltage across each capacitor. V1= ______ V2=_____ V3=____

Department of applied Physics and Astronomy Capacitors Bassam Rashed

 7- What is the relationship of voltages?

8- Using the stated capacitance (1.0x10-13 F, 2.0x10-13 F, 2.5x10-13 F) find the charge on each

capacitor. q1=____ q2=____ q3=____

9- Comment on your results of the stored charge with q1, q2, and q3.

10- What is the total capacitance in Farads? Read meter.

11- Use formula to find the total capacitance and compare to bar chart.

Department of applied Physics and Astronomy Capacitors Bassam Rashed