Electric Fields and Electric Potential
Prepare a lab report on electric fields and electric potential after you have completed the experiment below.
Part 1: Two Round Conductors
Gather all items required for the exercise.
Note: If using the lab kit box, remove contents and place in a secure area.
Put on your safety goggles.
Center the black conductive paper on the top of the box, grid-side up.
Place the two metal nuts (conductors) at the (5 cm, 10 cm) and (20 cm, 10 cm) positions on the paper. Secure using two dissection pins for each conductor. See Figure 13.
Note: Place the pins close to the inner wall of the nut at opposite sides such that the conductors do not move. It is essential that the conductors are securely contacting the conductive paper.
A photo of a sheet of black conductive paper. A metal nut is positioned over the intersection of four squares. Two T-pins are inserted through the nut and paper such that their heads are resting on the top surface of the nut.
Figure 13. Securing conductor to conductive paper using two dissection pins. The pins are contacting the inner walls of the metal nut.
Insert the battery into its holder.
Attach jumper cables from the two conductors to the battery holder, one to the positive terminal and the other to the negative terminal. See Figure 14.
Note: You may need to adjust the pins or use additional pins to ensure the conductors are in consistent contact with the conductive paper and not moving.
A photo of a sheet of black conductive paper resting on top of the lab kit box. Two metal nuts are positioned on the surface of the paper and spaced three squares apart from each other. Each nut has two T-pins inserted through it. Alligator clips are attached to each nut, connecting the nuts to a battery holder. The battery holder is connected on one side to the negative probe of a digital multimeter. The positive probe of the meter is not touching the experimental setup.
Figure 14. Experimental setup with two circular conductors.
Attach the negative black lead from the digital multimeter (DMM) to the negative terminal of the battery holder using another jumper cable.
Set your DMM to the 20 DCV (DC Volts) setting.
Using the red lead, test the voltage readings of your conductors.
Touch the negative conductor. This should result in a zero reading.
Touch the positive conductor. This should result in a reading comparable to the voltage of the battery (between 1.2 V and 1.5 V, depending on the battery’s previous use).
Using one sheet of white conductive paper, draw the position of the conductors and label them with the voltage readings from your DMM.
Gently place the red lead between the two conductors and note the voltage reading. Record this position with a mark on your white paper.
Note: Avoid heavy contact between the DMM lead and the surface of the conductive paper. Holes or dents in the paper can affect measurements.
Move the DMM probe to find another location with the same voltage reading and mark the position on your white paper.
Repeat step 12 until you have at least six locations with the same voltage marked on your white paper.
Use a colored pen or pencil to connect the points made in steps 12 and 13 with a smooth curve and label the curve with the voltage.
Note: This curve represents an equipotential line.
Select a new position 2-3 centimeters from your first line and repeat steps 10-13.
Repeat step 14 until you have at least five distinct lines of different voltages.
Turn off the DMM.
Using a second colored pen or pencil, draw five or more electric field lines by connecting a line from the positive conductor to the negative conductor, intersecting with each equipotential line perpendicularly. Indicate the direction of the electric field on the drawing.
Take a photo of your drawing with your name and date. Upload the image in Photo 1.
Part 2: Two Parallel Conductors
Using the scissors, cut the aluminum foil into two 14 cm x 14 cm sheets.
Fold each piece of foil in half to form a rectangle.
Note: Ensure that the shiny side of the foil is facing outward.
Fold each piece of foil again lengthwise into thirds. This should result in two long, relatively narrow pieces of foil.
Create a tab on each piece of foil by folding approximately 1 cm of one end two times. Fold the tabs such that they make a right angle with the strip. See Figure 15.
Figure caption is an adequate description of the image.
Figure 15. Strip of foil with tab at a right angle.
Wipe the foil strips with a paper towel so they are free of fingerprints.
Disconnect the jumper cables from the metal nuts used in Part I and remove the pins securing the nuts to the box. Set the nuts aside.
Place the foil conductors on the conductive paper such that they are parallel, centering them at (5 cm, 10 cm) and (20 cm, 10 cm).
Secure the foil conductors with 2-3 pins, ensuring that they lay flat, in contact with the conductive paper.
Attach the jumper cables to the tabs of each foil strip. See Figure 16.
Note: Ensure that the jumper cables do not touch the conductive paper.
The image contains two photos. The left photo is of two strips of foil pinned to a sheet of black conductive paper positioned on a lab kit box. The strips are separated by three squares from each other. Alligator clips are attached to the tab of each strip, connecting the strips to a battery holder. The battery holder is connected on one side to the negative probe of a digital multimeter. The positive probe of the meter is not touching the experimental setup. The right photo is a close up of the metal strip showing the two pins pressed through the strip and the alligator clip attached to the tab.
Figure 16. Experimental setup with two parallel conductors (left) and closeup of one conductor with its tab at a 90° angle attached to a wire (right). The wire and conductor tab do not touch the conductive paper.
Using the red lead, test the voltage readings of your conductors with the DMM in the 20 DCV setting.
Touch the negative conductor. This should result in a zero reading.
Touch the positive conductor. This should result in a reading comparable to the voltage of the battery.
Using the other white conductive paper copy, draw the position of the conductors and label them with the voltage readings from your DMM.
Place the red lead between the two conductors and note the voltage reading. Record this position with a mark on your white paper.
Move the red lead to find another location with the same voltage reading and mark the position.
Repeat step 32 until you have at least six locations with the same voltage marked on your white paper.
With a color pen or pencil, create an equipotential line by connecting the marked locations on the paper.
Repeat steps 31-34 until you have five distinct lines of different voltages.
Turn off the DMM.
With a color pen or pencil, draw five or more electric field lines. Indicate the direction of the electric field.
Note: This is done by drawing a line from the positive conductor to the negative conductor such that it intersects with each equipotential line perpendicularly.
Take a photo of your drawing with your name and date. Upload the image in Photo 2.
Cleanup:
Disconnect all jumper cables and remove the pins.
Return all HOL supplied materials to the lab kit for use in future experiments.
