# Coulumbs Law Lab Report Essay

1012 Words
Mar 12th, 2014
5 Pages

Coulomb's Law

1. Objective - To study the validity of Coulomb’s law on a simple electroscope. This will be split into two parts; first measuring the the force as a function of distance, and second we will look at how the magnitude and sign of the charges affect the force.

2. Theory- As is well known, like charges repel and opposite charges attract. That being said, the strength of those forces also depends on the distance between the two charges. By observing this force over countless experiments Charles-Augustin de Coulomb discovered an inverse square law relating the force between two charges to the distance between them. This relationship is described by

1. Objective - To study the validity of Coulomb’s law on a simple electroscope. This will be split into two parts; first measuring the the force as a function of distance, and second we will look at how the magnitude and sign of the charges affect the force.

2. Theory- As is well known, like charges repel and opposite charges attract. That being said, the strength of those forces also depends on the distance between the two charges. By observing this force over countless experiments Charles-Augustin de Coulomb discovered an inverse square law relating the force between two charges to the distance between them. This relationship is described by

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This is the first data point

2.Reduced the charge on the left guide sphere by half. To do this, grab the unused right guide block sphere and ground it using your finger, then remove your finger and touch the two spheres together. they now each have half the initial charge.

3. Now reposition the left guide guide block sphere to the previous value of r and record the new value of d.

4. Repeat this process two more times with 1/4 and 1/8 the original charge.

5. Experimental Results

Part 2 Fe Calculation:

Graph 1 - Force vs. Sphere Separation

Graph 2- Force vs. 1/r^2

Graph 3 - Log of Force vs. Log of 1/r^2

Part 3 Graph 4 - Fe/Fo vs. q/q0

Charge calculation -

6. Questions Part 1 - a.What would happen if in step 2-c, you remove the charged strip from the vicinity of the sphere before your remove your finger from the sphere?

b. What we have just done is charging by induction. In your own words describe what is happening in panels a through e in figure 2.

c. The gray spheres are styrofoam with a conductive coating. Why do we need the spheres to be conducting?

d. Does the suspended force experience a force? Can you explain why the suspended sphere would experience a force even though it has no net charge? Doesn’t this contradict Coulomb's Law which says that you need two charged objects to have a force?

e. Notice in the left panel of

2.Reduced the charge on the left guide sphere by half. To do this, grab the unused right guide block sphere and ground it using your finger, then remove your finger and touch the two spheres together. they now each have half the initial charge.

3. Now reposition the left guide guide block sphere to the previous value of r and record the new value of d.

4. Repeat this process two more times with 1/4 and 1/8 the original charge.

5. Experimental Results

Part 2 Fe Calculation:

Graph 1 - Force vs. Sphere Separation

Graph 2- Force vs. 1/r^2

Graph 3 - Log of Force vs. Log of 1/r^2

Part 3 Graph 4 - Fe/Fo vs. q/q0

Charge calculation -

6. Questions Part 1 - a.What would happen if in step 2-c, you remove the charged strip from the vicinity of the sphere before your remove your finger from the sphere?

b. What we have just done is charging by induction. In your own words describe what is happening in panels a through e in figure 2.

c. The gray spheres are styrofoam with a conductive coating. Why do we need the spheres to be conducting?

d. Does the suspended force experience a force? Can you explain why the suspended sphere would experience a force even though it has no net charge? Doesn’t this contradict Coulomb's Law which says that you need two charged objects to have a force?

e. Notice in the left panel of