Example Of Report On Electric Fields And Electric Potential I

Objectives

The Objective of this lab is to learn how to visualize electric fields using different electrode configurations which help to generate different electric fields. In this experimentation the mapping of electric equi- potential lines and electric field lines is done only for two dimensional charge configuration.

Procedure

A comprehensive procedure is used as per the material provided to us in the class. Basically, this experimentation is in 2 parts as described. In the first part there are a set of charged conductors in a water tank used to create an electric field. A digital Multi- Meter (DMM) is used to measure voltage drop between a fixed location and a set of varying locations in the tank and then equi-potential lines are drawn. The source or the electrodes are actually two metal bars. The charge is built up between these electrodes.
In the first part the ring in between is not used and the contours are noted in this fashion. An AC signal is generated between the bars. Red DMM lead is used to measure the RMS voltage at various locations in the tray as shown above. The readings are recorded in the graph.The equi-potential points are traced. The points are traced in the upper and lower parts of the tray. Enough locations are found and plotted. As shown in the above figure, the voltages are recorded on the paper. Next set of readings are for the 2 point probes. Largest possible RMS is recorded by rotating the probe appropriately. In part 2 a ring is added half way between the bars. Again the same procedure is repeated to measure the RMS. The value is also noted at the centre of the ring as well as several other locations within the ring.The voltages are recorded as shown above on the paper itself.

Experimental Data

The data is represented in the below table:
In the data set the potential difference between any two points is assumed to be ± 0.2V. This difference is due to the experimentation value and depends on how the hand is aligned and how accurately the probe is placed on the centre of the dots, which could affect the results. The points in the same equi-potential lines are taken to either form the line or the circle (when the ring is placed). All the data is in 2D, although the electric field itself is in 3D, so this in itself is the potential cause of some errors that may have crept in due to the data collection.

Results:

The calculations are shown in the tabular format for various points in single probe and double probe.
The following equation is used for parallel electrodes: E= ΔV / Δx.

Analysis and discussion

In this experimentation, the electric fields were studied with different electrode configurations. The experimentation was done in two parts, the first part using the parallel electrodes, without the ring and the second part constituted the ring placed in between the electrodes. The object was to observe the resultant fields and their respective strengths as measured by the Multi Meter. The probe was placed in between the electrodes, and when the probe was moved parallel to the probes, the orientation of the electrode could not cause any change in the voltage. However, when the probe was moved perpendicular to the electrodes, there was significant change observed in the voltages. The change was maximum when the probe was moved from the positive electrode to the negative electrode.
The field lines, are perpendicular to the equi- potential lines. The equi- potential lines forms rings around the 10V charge in the center, since the field lines extends outwards in all directions. When the probe was kept touching the electrode, there was a very low voltage observed rather than a 0 volt reading. The probe outside of the electrodes showed no charge, proving that the charge existed just in between the electrodes only. In the second part of the experimentation, a ring is placed in between the parallel electrodes and similar examination is done. When the probe is moved radially from the outer circumference of the ring towards its center, there was maximum voltage change. However, when the probe is moved in circle along with a constant distance with the circumference of the circle, there was no change in the voltage. From the probe, it was also noted that the electric charge outside the circle had no effect of the ring.
The electric fields will behave in similar manner in both the cases. When the voltage is decreased the concentration towards the negative will decrease in all the cases. When the voltage is increased, the concentration also gets increased at the negative terminal. The concentration will also increase as the voltage increase in the insulated ring.

Conclusion

The equi- potential line and the field line is possible to be drawn with the help of data collected with the experiment. The presence or absence of a second field will also influence the field lines and the equi- potential lines. If the electric potential, no matter of what value is same in between the electrodes, there will be no field present. The field presence and absence is directly related with the potential difference between the electrodes. The electric fields are perpendicular to the surface of electrodes. When collecting the data, positioning of the probe could account for some of the error accumulated.