annotated-PHYS%20122-%20Lab%201%20Report%20Draft

Name(s): Kirsten North Date: 09/03/2023 Electric Force vs Distance Lab Purpose Conduct an experimental investigation to establish the correlation between electric charge, the separation distance between charged particles, and the resulting electric force. Apparatus - Coulomb’s Law lab simulation: https://phet.colorado.edu/sims/html/coulombs- law/latest/coulombs-law_en.html This photo shows part of the simulation when both charges are negative. This photo shows part of the simulation when one charge is negative and the other is positive.

Name(s): Kirsten North Date: 09/03/2023 Procedure 1. Access the simulation: Open the Coulomb’s Law simulation from the link above. 2. Setting up the experiment: After launching the simulation, make sure that it is set to the atomic scale. 3. Recording charge values: Start by recording the initial values of both charges selecting any non-zero values. 4. Varying distance: Adjust the separation distance between the two charges incrementally, with increments of 10 picometers (pm). After each adjustment, record the magnitude of the electric force exerted between the charges in a table. Note the sign of each charge (positive or negative) and determine whether the force is attractive or repulsive. 5. Independent and dependent variables: In the experiment, consider the distance (r) between the charges as the independent variable, as it is intentionally changed. The electric force (F) is the dependent variable since it is influenced by the changes in distance. 6. Data analysis with nPlot: Use nPlot to create a plot and examine any patterns or relationships. Plot the force (F) in micro-Newtons (μN) on the vertical axis and the distance (r) in meters (m) on the horizontal axis. 7. Curve Fitting: Fit the data to an inverse square curve using nPlot, and express the equation of best fit for this curve. Include units for the fit coefficient. 8. Calculating units of fit coefficient: Determine the units of the fit coefficient in the equation and record its value. Convert these units to SI units. 9. Calculating a new quantity: Divide the SI fit coefficient by the product of the charges while also using SI units for charge. Note the units and value of this new calculated quantity. Identify the term by which this is known. 10. Calculate percentage error: Compute the percentage error in the calculated quantity to access accuracy in results. 11. Repeat with altered charge: Go to sheet 2 in nPlot and double one of the charges in the simulation. Repeat all the steps above, including curve fitting. Now there should be two curves on the graph. Record the values of both charges. Data Trial 1: Charge 1 (e) Charge 2 (e) Distance (pm) Distance converted (m) Magnitude of Force (N) Force converted ( μN) -3 -6 10 1 x 10 -11 4.15 x 10 -5 41.5 -3 -6 20 2 x 10 -11 1.04 x 10 -5 10.4

Name(s): Kirsten North Date: 09/03/2023 - Curve Fitting: Express the equation of best fit for this curve. ࠵? = ࠵? ∗ 1 ࠵? ! - Calculating Units: What are the units of the fit coefficient in the equation of the line that was written? What is the value? The units of the fit coefficient k will be in μN*m 2 because F is measured in micro-Newtons and r is measured in meters. The value is ࠵? = 8.222 x 10 22 μN*m 2 . Calculating k for each data point r (m) F (μN) k (μN*m 2 ) 1 x 10 -11 41.5 4.15 x 10 23 2 x 10 -11 10.4 2.60 x 10 22 3 x 10 -11 4.61 5.12 x 10 22 4 x 10 -11 2.60 1.625 x 10 21 5 x 10 -11 1.66 6.64 x 10 20 6 x 10 -11 1.15 3.194 x 10 20 Calculating k average: k average = k total /6 = 8.222 x 10 22 μN*m 2 - Calculating New Quantity: Change the units of the fit coefficient to SI. Divide that by the product of the charges. What are the units of this new, calculated quantity? What is the value? What is the name by which we refer to this quantity? The units of the new quantity are N*m 2 /C 2 which we refer to this as Coulomb’s constant. Coulomb’s constant is 8.988 x 10 9 N*m 2 /C 2 . The calculated K is = 4.567 x 10 9 N*m 2 /C 2 . Convert k to SI units: 1 μN = 1 x 10 -6 N 1 μm 2 = 1 x 10 -12 m 2 k SI = 8.222 x 10 4 N*m 2 Product of charges: Q 1 * Q 2 = (-3) * (-6) = 18 C 2 ࠵? = " #$ ∗ #! = 4.567 x 10 9 N*m 2 /C 2 - Calculate percentage error in the above quantity. Percent error = % ࠵?࠵?࠵?࠵?࠵? = |(.*+, - $. ! /0.100 - $. ! | 0.100 - $.^1 * 100 = 49.19 %

Name(s): Kirsten North Date: 09/03/2023 Data of Charge 1 Doubled Charge 1 (e) Charge 2 (e) Distance (m) Force ( μN) -6 -6 1 x 10 -11 83.1 -6 -6 2 x 10 -11 20.8 -6 -6 3 x 10 -11 9.23 -6 -6 4 x 10 -11 5.19 -6 -6 5 x 10 -11 3.32 -6 -6 6 x 10 -11 2.31 This graph displays additional data points obtained when one of the charges was doubled, along with the previously plotted inverse square curve and data. - New fit coefficient: Find the new fit coefficient by the product of the charges. Calculating k for each new data point r (m) F (μN) k (μN*m 2 ) 1 x 10 -11 83.1 8.31 x 10 23 2 x 10 -11 20.8 5.20 x 10 22 3 x 10 -11 9.23 1.025 x 10 22 4 x 10 -11 5.19 3.24 x 10 21 5 x 10 -11 3.32 1.328 x 10 21 6 x 10 -11 2.31 6.416 x 10 20

Name(s): Kirsten North Date: 09/03/2023 The relationship investigated in this experiment involved electric charge, separation distance between charged particles, and the resulting electric force. It was determined that the electric force follows an inverse square relationship, as shown by the equation ࠵? = ࠵? ∗ $ 3 " where F is the force, k is the electric force constant, and r is the distance between charges. The electric force constant ( k ) represents how strong the electric force is and changes with distance. 3. Describe the meaning of the term electric force constant in your own words, as it pertains to this experiment. Provide the value and units for the electric force constant. The electric force constant in this experiment tells us how strong the electric force is between charged particles and how it changes with the distance between them. It measures how strong the electric force is when we have certain charges set up. After doing the experiment and looking at the data, it was found that the electric force constant is (insert value) μN*m 2 . This number shows us how force and distance are connected in this particular situation.