Electric Field Lab

Purpose

To become familiar with electric forces and electric fields.

Introduction

For this activity, you will use the PhET Interactive Simulation Charges and Fields 2.04 to investigate an electric field at various distances around a charge. This simulation has both positive and negative charges to place in the field. All charges are 1 nanocoulomb (1 nC = 1 x 10-9 C). 

There is also electric field sensors that can be placed in the field. These sensors give the magnitude of the electric field strength in volt/meter (V/m). Recall from the Electrostatic Presentation that electric field strength is calculated using the following equation:

One volt/meter is equal to one newton/meter (N/M). Electric field strength is a vector quantity, therefore the electric field sensors also give the direction of the electric field.

Materials

An internet-connected computer

Procedure

Part 1 - Electric Field Lines

1. Open the simulation. In the lower right-hand corner, check Show E-field, grid, and Show numbers.
2. Take a few minutes to put charges in the field and note what happens to the field lines as charges are moved around.
3. Arrange the charges as shown in the Data Table 1 below. Draw the electric field lines using arrows for each arrangement.
4. Be sure to clear your charge(s) before going on to the next arrangement.

Part 2 - Electric Field Strength

1. Make certain all charges are off of the field, and the Show E-field, grid, and Show numbers options are selected.
2. Place a positive charge on the grid so it is on two dark lines.
3. Place E-Field Sensors at the coordinates shown in Data Table 2 below.
4. Use the information given by the E-Field Sensors to complete the data table.
5. Clear the field, and place a negative charge on the grid so it is on two dark lines.
6. Repeat steps 2-3 for Data Table 3.
7. Again clear the field. Place a positive and a negative charge on the grid so they are 2 meters apart, with the positive charge on the left and the negative charge on the right. Assume the positive charge is at coordinate (0,0).
8. Repeat steps 2-3 for Data Table 4.

Data

Table 1: Electric Field Lines

Data Table 1 continued

Data Table 2: Electric Field Measurements for a Positive Charge

Data Table 3: Electric Field Measurements for a Negative Charge

Data Table  4: Electric Field Measurements for a Positive Charge and a Negative Charge

Analysis and Conclusions

1. Using the information in Data Table 1, describe the direction of an electric field.

2. Compare the electric field strength in Data Table 2 (with a positive charge) with data Table 3 (with a negative charge).

3. Compare the direction of the electric field in Data Table 2 (with a positive charge) with data Table 3 (with a negative charge).

4. Using the information given in Data Table 4, explain how opposite charges affect the electric field in both magnitude and direction.

Optional Challenge

Use the simulation to create an electric field strength vs. distance graph.