Hall Effect Experimental Results Issue

[K29]

One of the simple experiments for simply observing Hall effect was done. However, I have a problem with the experimental results (attached .xls)

First the current in the solenoid was varied while the current in the Hall Probe was constant. Then the current in the Hall Probe was varied while the solenoid current was kept constant.

1.) (Ignore the Helmholz for now)Looking at the left most table. There is a slight negative potential for the low solenoid current values. When the solenoid current was set to 0, and the Hall probe was switched on there was this small negative voltage. There is nothing wrong with the calibration of the voltmeter, as when the current is decreased to 0, the negative potential slowly vanishes. What causes this?

2.) I am trying to identify the mistake made with the Helmholz results. The cables were never switched around at any time. What is going on here? It is possible that we accidentally flipped the Hall Probe over before doing the last Helmholz results, but this would simply result in the Hall Voltages to have a change in sign, not to go in entirely the wrong direction!

Please help. Thanks in advance.

 

[member 553083]

1.) The small negative potential when the solenoid current is set to 0 may be caused by a few different factors. It could be due to the fact that the Hall effect probe is sensitive to magnetic fields and when the solenoid current is set to 0, there is still a residual magnetic field present in the area. It could also be due to a small offset voltage present in the voltmeter being used. 2.) The results from the Helmholz coils are likely incorrect due to either a wiring mistake or a calibration error. If the cables were switched around at any point, this could have caused the readings to be off. Additionally, if the calibration of the voltmeter was not done correctly, this could also lead to incorrect results. It is also possible that the Hall Probe was not placed correctly in the coil when the measurements were taken, resulting in an incorrect reading.