Partner: Rachel Beckner
TA: Joel Mazer
March 15, 2012
This experiment clearly demonstrated how Ampere’s Law relates the magnetic field to the current using the relationships stated in the formula B= μ0I2πr. This relationship allowed to the experiment to calculate the value of permeability of free space in order to verify the relationship that is outlined in Ampere’s Law. This lab also allowed us to measure magnetic field strength as a function of the distance measured perpendicularly from a long current-carrying wire.
We found that there is a linear relationship between B/I and 1/r, which can be seen by the graph and is predicted by Ampere’s Law. The data from this experiment produced a plot of B/I vs 1/r with a regression with a r2of 0.9698, which indicates a highly linear relationship. Our slope was also only off by 0.0175% which indicates that this was a highly successful lab. There, as usual, are sources of error that can be seen. The magnetic field strength, B, was determined by multiplying the output voltage of the magnetoresistive sensor by its determined calibration constant. If the sensor were calibrated improperly, then this would result in a systematic error that would cause the data to remain linear as it should, but would affect the slope. This would cause the value for μ0 to be incorrect. Another source of error could be due to the extremely small changes in distances. It is very difficult to move an object exactly 0.1 cm, which would cause a slight error. Another source of error for our particular experiment may be due to the ammeter. The value would not stay constant, even when the radius remained the same. It was difficult to get a steady reading from this. These last two sources of error would also have changed the slope of the linear regression equation.