Magnetic Fields and Forces

     The first thing we did in lab on Wednesday was observe the behavior of a compass when it was placed in proximity of a bar magnet. The arrows drawn on the whiteboard represent the direction of the red portion of the compass needle as it was moved in a circle around the magnet. The purpose of doing this was to get an idea of what a magnetic field looks like. 

     This is a more accurate depiction of what a magnetic field actually looks like in two dimensions. Iron shavings were placed around the bar magnetic, and they arranged themselves in the pattern shown. The field lines are nearly linear as they leave the north pole of the magnet and curve around the length of the magnet before straightening out again as they reenter the south pole. 

     This picture shows three different enclosed surfaces drawn around certain points of the magnetic field. The surface drawn to the left and the surface surrounding both poles have a net flux of zero because the same amount of field lines enter them as do exit them. The surface containing only the south pole does have a net flux of 10. However, it is important to note that a monopole magnet does not exist in nature. 

 

     These are the calculations performed to find the strength of the magnetic field in an experiment that I should have taken a picture of.  Essentially, the experiment consisted of a magnetic force created from a current running through a wire and a magnet and a hollow copper rod that rolled off a platform upon experiencing the force. All of the measurements we needed are written down toward the lower right hand corner of the white board. The final equation we derived to calculate the strength of the magnetic field is shown in green, and the answer we came up with was roughly .0207T, which seems reasonable.

     There was also another demonstration which I neglected to take a picture of. This demonstration consisted simply of a magnet and a wire with a current running through it, and we were supposed to predict which direction the magnetic force would cause the wire to move in.