# PHYS 206 Bethune Cookman Univ

I’m working on a physics report and need support to help me understand better.

In these calculations, the Coulomb constant has a value of 8.99×109Nm2C2

$8.99\phantom{\rule{0ex}{0ex}}×{10}^{9}\phantom{\rule{0ex}{0ex}}N\cdot \frac{{m}^{2}}{{C}^{2}}$

Part I (Label the tab “macro”): This is the macroscopic data. Note that: q1=q2=q.

${q}_{1}={q}_{2}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}q.$

Starting in cell D2, record all of your force measurements down the D column. In cell A1, record the initial position of q1. In cell A2, record the initial position of q2. The difference in those positions is the first separation between the charges. Place this value in B2. In cell B3, type (without quotes) “B2+0.1”. Hit enter. Copy the formula down to the last force measurement. Finally, in cell C2, type “B2/100”, and copy the formula down.

1.Place column labels in cell 1. In cell C1, it is r(m)

$r\left(m\right)$

. In D1, it is F(N)

$F\left(N\right)$

.

2. Plot F(r)vs.r

$F\left(r\right)\phantom{\rule{0ex}{0ex}}vs.\phantom{\rule{0ex}{0ex}}r$

. Make sure you insert the correct graph! It looks like in inverse-square curve. Label the graph for presentation. Afterwards, run a trendline by right-clicking the data. Chose power fit. Place the equation on the graph and enhance the size. Note the power of the fit. Record and label on the spreadsheet close to the graph the power obtained and the coefficient. Note: Do NOT run a LINEST or linear fit here!!!!!

For this analysis, using the Coulomb equation and this coefficient, calculate q. Record this value in SI based units as well as in micro-Coulombs.

Part II (Label a new tab “micro”): You are given that q2=4e

${q}_{2}=4e$

. Note that this scale is now in picometers.

Starting in cell D2, record all of your force measurements down the D column. In cell A1, record the initial position of q1. In cell A2, record the initial position of q2. The difference in those positions is the first separation between the charges. Place this value in B2. In cell B3, type (without quotes) “B2+0.1”. Hit enter. Copy the formula down to the last force measurement. Finally, in cell C2, convert first value to meters, and copy the formula down.

1.Place column labels in cell 1. In cell C1, it is r(m)

$r\left(m\right)$

. In D1, it is F(N)

$F\left(N\right)$

.

2. Plot F(r)vs.r

$F\left(r\right)\phantom{\rule{0ex}{0ex}}vs.\phantom{\rule{0ex}{0ex}}r$

. Make sure you insert the correct graph! It looks like in inverse-square curve. Label the graph for presentation. Afterwards, run a trendline by right-clicking the data. Chose power fit. Place the equation on the graph and enhance the size. Note the power of the fit. Record and label on the spreadsheet close to the graph the power obtained and the coefficient. Note: Do NOT run a LINEST or linear fit here!!!!!

For this analysis, using the Coulomb equation and this coefficient, calculate q1

${q}_{1}$

. Record this value in SI based units as well as in micro-Coulombs. Also, record the polarity. Is it is negative or positive ion? How do you know?

4. Plot F(r)vs.1r2

$F\left(r\right)\phantom{\rule{0ex}{0ex}}vs.\phantom{\rule{0ex}{0ex}}\frac{1}{{r}^{2}}$

. Is it linear? Label the graph for presentation. Run a LINEST by highlighting a 2 x 5 matrix starting around cell A15 or so. Record the value of the slope and the uncertainty (e.g. 2.5±0.1

$2.5\phantom{\rule{0ex}{0ex}}±0.1$

).

For this analysis, using the slope and the Coulomb constant, calculate q1

${q}_{1}$

. Record this value in SI based units as well as in micro-Coulombs. Also, compare with your first calculation and comment.

Part III (Create a tab called “summary”): Insert large text boxes to type in.

In the summary tab, address these questions:

• From the data (you) collected, does the power fit indeed illustrate the inverse-square Law?
• Suppose you placed another charge (q3
${q}_{3}$

) on the opposite end of the ruler of (a) equal value as q1

${q}_{1}$

and with the same sign and (b) a charge q3=2q1

${q}_{3}=2{q}_{1}$

.

Describe how the force on q2

${q}_{2}$

would look as a function of position starting at the original point as before, and then moving towards the right for both scenarios (a) and (b)? Analyze one scenario at a time! Take a stab at it. How would you begin to investigate this?

• Suppose you were in a lab doing these measurements, assuming well-calibrated equipment, list some random errors you would encounter.