Posted: September 20th, 2022


Lab5-coulombslaw2 x

Lab 5 – Intro to Coulomb’s Law

The Coulomb constant “k” is named after Charles-Augustin de Coulomb. This constant is associated with the electric force and is also known as the electric force constant. When charged particles interact, a force repels or attracts the particles. For instance, two like charges (such as a proton and a proton) repel each other and travel in opposite directions and two unlike charges (such as an electron and a proton) will be attracted to each other. The electrostatic force equation is shown below:

Objective: Find the Coulomb Constant.

We will use the simulation below:

Figure 1: Coulomb’s Law simulation. PHYSICS II LAB

Directions: Answer the following questions.

1. What is the equation for Coulomb’s Law?


. Define each variable in the equation.

3. As the distance between electric charges increase, the electric force:

a. Increases

b. Decreases c. Remains the same


. As the distance between electric charges decrease, the electric force:

a. Increases b. Decreases c. Remains the same

5. Like charges:

a. Repel b. Attract c. None of these


. Unlike charges:

a. Repel b. Attract c. None of these


1. Go to the following site to access the lab simulation for Coulomb’s Law and download the simulation.

2. open it

3. select Macro Scale

4. Set charge 1 to


𝜇𝐶 and set charge 2 to 1𝜇𝐶. Remember 1 𝐶=1×106 𝜇𝐶

5. Make sure force value box is checked.

6. In data table 1 below the separation distance “r” is given to you. Separate the charges by 10 cm.

7. Record the force value in data table 1. It does not matter which force value you use since you are only recording the magnitude of that force.


. Repeat the process for the rest of the values.

9. Record the value for the separation distance in meters. Record your values in data table 1.

10. Find 1/r2. Record your values in data table 1.

Value of 𝑞1=________________________ 𝑞2=________________________

r (cm)

r (m)

F (N)

1/r2 (m-2)


Data Analysis

1. Once you have completed data table 1, make a graph of Force vs. Separation Distance. You do not need to put an equation and fit on this graph. You can use Excel or LoggerPro. Include with report.

2. Make a second graph of Force vs. 1/r2.

3. Use the Force vs. 1/r2 graph to find the value of the Coulomb Constant “k”. Include graph with linear fit in report.

Show work here:

4.Calculate the percentage error in k. Use the following equation to calculate the percentage error. Show your work!!!!!

% 𝑒𝑟𝑟𝑜𝑟=|𝑒𝑥𝑝𝑒𝑟𝑖𝑚𝑒𝑛𝑡𝑎𝑙 𝑣𝑎𝑙𝑢𝑒−𝑎𝑐𝑐𝑒𝑝𝑡𝑒𝑑 𝑣𝑎𝑙𝑢𝑒| / 𝑎𝑐𝑐𝑒𝑝𝑡𝑒𝑑 𝑣𝑎𝑙𝑢𝑒 ×100%

5. Watch the video “Spinning Nanofibers to Improve N-95 Masks” on electrospinning. Explain what this process is in the space provided below. How is the electric force used in this process?

Video: Spinning Nano fibers to improve N-95 masks

© 2021 Dr Dipti Sharma. Website is taken from PhET.




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