PHY 112 LAB #3 PDF

Preview

Summary

Lab 3 for PHY 112 ...

Description

Lab #3

Equipotential Mapping Name:

Giselle Sierra

Purpose:

 n electric field is a vector quantity as it contains both a direction and a magnitude. It produces a force A between two charges which we call the electric potential. Electric potential is not a vector quantity, as it only has magnitude; which would be distance. Essentially electric potential is defined as the ratio of energy per charge that is needed to move a test charge to a certain position(“Energy and Potential”, n.d.). We know electric potential as voltage (V), and it is measured in volts (V). In a uniform field you could determine this electric potential by using the following equation: V   = Ue / q (“ Energy and Potential”, n.d.)..

Class:

PHY 112

Date: 09/13/20

Now, in order to make it easier and allow us to visualize this in a qualitative way we use equipotential mapping or equipotential diagrams to draw an electric field to show where positions of equal potential are(“Energy and Potential”, n.d.).. It allows us to visualize it in 2D. One thing to note about these diagrams is that electric field lines are always perpendicular to the equipotential lines. Electric field lines radiate out from a positive charge and end on negative charges (“Energy and Potential”, n.d.). The purpose of this lab is to examine the potentials at various positions between both a positive and a negative point source. We will create this by creating a voltage difference between two points and measuring it with a voltmeter. We will then create two graphs, a contour graph and a 3D graph. I predict that we will in fact be able to obtain both positive and negative obviously dependent on position. Due to the fact that the system we are creating is made up of both positive and a negative point sources we are more than likely going to have a variety of opposite values. Procedures:

Apparatus :

Required Materials :

● ● ● ● ● ● ● ● ●

●

9V battery 9V battery connector 2 insulated wires with alligator clips Voltmeter Styrofoam base 2 nails Flat-bottomed plastic container Permanent marker Tape Water

1. Open a new excel worksheet and set it up so that it looks like the styrofoam block grid lines, each column labeled with a letter and each row labeled with a number. (Make sure the grid is 1 cm x 1 cm) 2. Take the two nails from your lab kit and place them on the styrofoam about 5 cm apart. 3. Find the halfway point between the two nails and mark this location. This will be your zero point location.

4. Obtain a plastic flat-bottomed container that can fit your styrofoam grid a few inches above water. Tape it to the bottom so that it is not floating. The water should rise about 1 cm above the top of the styrofoam grid. 5. Now, connect the tops of the two nails with the insulated wire with an alligator clip. 6. Next, connect the other end of the wire to the 9V battery connector. 7. Then, you need to convert your multimeter into a voltmeter. 8. Connect the battery to the battery connector and test the setup. The voltmeter should read 9V. 9. Once everything is set up correctly, you can start taking data. 10. Place the black voltmeter at the halfway point of the two nails then place the red lead in the middle of the first grid space in the water. Record the voltmeter reading. 11. Move the red voltmeter lead to the next square and record the voltmeter reading. Repeat these steps until all squares have been measured. 12. Once done, make sure to allow the battery to cool down and disconnect everything. 13. Using the voltmeter readings taken create a contour graph and a 3D graph.

Data:

Evaluation of Data:

Calculatio ns:

N/A -There were no manual calculations required for this lab, instead an excel worksheet was created in order to record the voltage potential in various locations and then a contour graph and a 3D graph were created.

Graphs:

Results:

●

● ● Conclusions:

A contour and 3D surface equipotential graph was successfully created, which displayed the voltage potential at a negative point source; a positive point source was not. A voltage difference between two points was created using a battery A voltmeter helped in determining the potential at various points

 he purpose of this lab was to examine the potentials at various positions between a positive and T negative point source. This was shown visually on the two graphs created. With the exception that we were only able to obtain negative sources and not positive. This was a helpful lab as it allowed students to brush up on their excel graphing and analytical methods. For me, it was difficult setting up the graphs. At first, I had accidentally made both graphs in 3D. Then the options I had to choose from such as stock, surface or radar all looked drastically different so I was unsure which option suited the data best. Some sources of error in this experiment include but are not limited to, the plastic container not staying down (due to the tape used). Because I used a battery from home, another source of error could have come from the battery burning out. This is most likely the reason why the numbers were large in the beginning and then decreased. Because only negative potential was displayed the objective of this lab was not met. I am however aware of what a contour graph should have looked like. Based on the possible errors, I believe if I were to recreate this experiment again I could get both positive and negative potentials and a correct contour graph.

Analysis Questions: 1. At what grid position should you place a positive particle so that it has the largest potential? At what position would you place a negative particle? Explain. I would place it as close to the nail as possible as that is where most of the voltage source is coming from. A negative particle would be placed at the negative site and I would also place it near the nail where the actual negative source is running. 2. Describe how your results would change if you used a 12V car battery instead of a 9V battery. Be specific and explain your answers. If a 12V car battery had been used instead of a 9V battery, the voltage numbers would increase significantly and would allow the experiment to run much longer; we would also be more likely to actually obtain both a positive and negative source. 3. Describe how your results would change if you placed the black voltmeter lead at the negatively charged nail rather than at a point halfway between the two nails. Be specific and explain your answers. If you were to move the black voltmeter lead to the negatively charged nail instead of at the halfway point there would be a drastic shift in the data and cause the electric field direction to change. The purpose of placing the black voltmeter at the halfway point is to create a zero potential in order to distinguish the values. 4. If you placed a particle with a charge of +4 μC at position D3 on your grid, how much electric potential energy would the particle have? Show your work. Did work occur on or by the particle to move the charge to this position? Explain your answer.

V=Kq/ r2 V= (9*10^9)(4*10^-6)/( 22 ) V= 9000 Work did in fact occur. This is due to the positive charge going towards the positive source.

References:

Energy and Potential.(n.d.). In Physics II [Online Lesson 3]. https://www.riolearn.org...