Physics Lab: Electric Field (attached below) P/s: Need to attach pictures when doing experiment. 1/3 Lab 2: Electric Field Objectives In thi
Physics Lab: Electric Field
(attached below)
P/s: Need to attach pictures when doing experiment. 1/3
Lab 2: Electric Field
Objectives
In this lab you will use PhET’s simulation Charges and Fields to study the electric field produced by
discrete charge distributions.
Part 1: Field Due to a Point Charge
1. Uncheck the box for Electric Field.
2. Check the boxes to display Values and the Grid. Make sure these are the only boxes checked.
3. Place a +1-nC charge toward the center of the simulation.
4. Distribute 8 sensors evenly around the point charge. Use the tape measure to place each
sensor at a distance of 1 m from the point charge. All sensors should be the same distance
from the point charge. For each sensor, the value in V/m is the magnitude of the electric
field. Note that 1 V/m stands for 1 volt per meter, and 1 V/m = 1 N/C. The angle in degrees
is the direction of the electric field relative to the + -direction, with positive angles being
counterclockwise and negative angles being clockwise. Complete the following table by
recording the magnitude of the electric field read by each sensor.
5. Based on your measurements, does the magnitude of the electric field depend on the
direction of the field point relative to the point charge?
6. Place 7 of the 8 sensors back in their bin, keeping a single sensor in the simulation.
7. We now turn to investigate the dependence of the magnitude of the electric field on distance
from the point charge. Use the tape measure to place the sensor at each of the distances
shown in the table below and record the corresponding magnitude of the electric field.
8. Make a scatter plot of the magnitude of the electric field versus distance from the point
charge. Plot electric field along the vertical axis and distance along the horizontal direction.
Include the best-fit curve in your graph and the equation of the best-fit curve. Decide the
type of curve to fit the data with based on theoretical expectation. Are your results
consistent with theoretical expectation?
9. Place the sensor and the tape measure back in their respective bins.
10. Now check the box to display the Electric Field (not just its direction) and uncheck the Grid
box. How is the magnitude of the electric field represented? Describe the global structure of
the electric field (magnitude and direction) due to a positive point charge.
11. Use the simulation to compare and contrast the electric field of a single negative point
charge to that of a single positive point charge.
Sensor 1 2 3 4 5 6 7 8
Electric Field (N/C)
Distance (m) 0.25 0.5 0.75 1 1.25 1.5 1.75 2 2.25 2.5 2.75 3
Electric Field (N/C)
https://phet.colorado.edu/sims/html/charges-and-fields/latest/charges-and-fields_en.html
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Part 2: Field Due to an Electric Dipole
An electric dipole consists of a pair of equal and opposite charges.
1. Uncheck the box for Electric Field.
2. Check the boxes to display Values and the Grid. Make sure these are the only boxes checked.
3. Place a +1-nC charge and a −1-nC charge 2 meters apart along the horizontal. The positive
charge should be to the left of the negative charge. Take the origin of the coordinate system
to be at the midpoint of the two charges, with the -axis directed to the right and the -axis
directed up. Let and denote the and -coordinates of the field point, respectively. Let
be the magnitude of the electric field, and the angle the electric field makes with the + –
direction, with counterclockwise angles being positive and clockwise angles being negative.
4. Let us first investigate the electric field at field points on the horizontal line that passes
through the two charges. This line coincides with the -axis. Complete the following table.
Use a sensor for the measured values. Also calculate the magnitude and direction of the
electric field by adding the electric fields of each point charge.
5. In the above table, how do the measured values compare with the calculated values?
6. Let us now investigate the direction of the electric field at field points on the perpendicular
bisector of the line segment that joins the two charges. This line coincides with the -axis.
Complete the following table.
7. In the table above, how do the measured values compare with the calculated values?
8. Now complete the following table.
9. In the table above, how do the measured values compare with the calculated values?
10. Place the sensor in its bin.
11. Check the box to display the Electric Field (not just its direction) and uncheck the Grid box.
Describe the global structure of the electric field (magnitude and direction) due to an
electric dipole.
–2 –1.5 –0.5 0 0.5 1.5 2
Measured
Calculated
Measured
Calculated
x (m)
E (N/C)
θ (degrees)
–2 –1 0 1 2
Measured
Calculated
Measured
Calculated
y (m)
E (N/C)
θ (degrees)
–1 –1 1 2
–1 1 1 –1
Measured
Calculated
Measured
Calculated
x (m)
E (N/C)
θ (degrees)
y (m)
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Part 3: Field Due to a Pair of Positive Charges
1. Replace the charges in Part 2 with two +1-nC charges.
2. Repeat all the steps of Part 2 for this new pair of positive charges.
3. Compare and contrast the structure of the electric field of an electric dipole to that of a pair
of positive charges.
Part 4: Field Due to Three Nonlinear Charges
1. Place three point charges at locations of your choice. The three charges should not all have
the same sign, and they should not be arranged along a straight line. Choose the origin of
the coordinate system and use the same origin for both tables in this part. Indicate your
chosen charges and their locations in the following table.
2. Measure and calculate the electric field (magnitude and direction) at three different field
points of your choice. Complete the following table.
3. Compare your measured and calculated values in the table above.
Charge (nC) x (m) y (m)
First Charge
Second Charge
Third Charge
Measured
Calculated
Measured
Calculated
y (m)
E (N/C)
θ (degrees)
x (m)
