Helmholtz Coils and Magnetic Fields (original) (raw)

The objectives of the experiment are to determine the magnetic field along the horizontal x-axis that passes through the centre of a single solenoid coil, and to determine the magnetic field along the horizontal x-axis that passes through the centre of the Helmholtz coil. Helmholtz coil is a device that produces a region of a nearly uniform magnetic field. It consists of two solenoids that are parallel to each other on the same axis. Both solenoids are separated by a distance, d. Each coil carries an equal electric current in the same direction. The entire experiment is conducted via a simulator software provided. For Experiment I, the graph of B vs x is obtained alongside with the logarithmic graph of B vs the square of x. The comparison of the experimental and the theoretical logarithmic graphs allows the determination of the turns of wire, N of the hypothetical single coil. That is, N = 1717.5. It is managed to obtain the best value for B_0 through the standard deviation as the uncertainty in a single measurement with 70% confidence. That is, B_0 = (4.1267 x 10-3) ± (9.2236 x 10-5) T. The experimental μ_0 is deduced and it is given by μ_0 = (2.5292 x 10-7) T m A^-1. The determination of the experimental μ0 yields a percentage error of 79.9%. For Experiment II, the graph of B vs x is obtained for all d = R, d = 1.5R and d = 0.5R. Two major things found out in this part are, firstly, the mathematical erratum in either the simulator or in the laboratory manual is very substantial, and secondly, the erratum has caused such an ambiguity that a thorough quantitative analysis has become cumbersome given the time constraint as the deviation between the experimental and the theoretical values are of logarithmic. Next, the graph of B_0 vs d is also obtained for both the experimental and the theoretical values. Nothing much could be done on the quantitative aspect of it. However, qualitatively, it is observed that as d increases, B decreases. This may explain the lesser incident flux density as the coils move further apart. Lastly, the slope of the experimental data has a greater rate of change as opposed to that of the theoretical values.