For physics I have to examine the magnetic moment (M) of an inductor. We did an experiment with a torsion balans.We were given the formula: M N.I.S with N the numer of turns, S the surface of the inductor and I the current through the inductor.I have to make an error estimate on this value of M, and I can't figure out the error made on N (or is it possible there is no error on N?). We were also given a value of N 200.Can anyone explain me this ?
The number of turns, N, is not something you measure. You just count the number of turns of wires when you build the inductor or the manufacturer has it in the specification sheet. Unless you estimate the number of turns by count the number of loop per inch and measure the length of the inductor than there would be an error in the number of turns because you are estimating the loop density and measuring the length with a ruler. In your situation there is an error in I the current that is associated with the accuracy of reading the current from the meter and the accuracy of the meter. And S will have an error if you are measure that too. But usually for N is just something you can see an count then it is definite that number and there is no error. Or you take the word of the manufacturer or in your case by your professor or lab person. Another examples is if I try to determine the number of jellybeans in a jar. I could just count it and there would be no error unless I made a mistake. Or I could estimate by weighing a few beans and get their volume and then measuring the volume of the container, etc. As long as it is something definite and not a measured or estimated, then there is no error.
