Day 21 Lab 05/14/14

Magnetism Potential and Current:

In this experiments we did was seeing how the introduction of currents to find the magnetic field affect in a circular current loop. We have known knowledge prior to the past experiments so using those can help understand why the field changes when placed in a circle with current. This is similar to finding the electric potential of a point charge but however it is the magnets that provide the change and finding the magnetic field B we were introduced to a new equation that is similar to Gauss' Law but with constants related to magnetism. The field is caused because of the many moving charges which then as a result is the sum of each charge to field to find the value of the field. Throughout the lab we saw different scenarios in which this can occur like an infinite charged wire using integration, a square, or a ring that we use our prior knowledge to find the magnetic field due to current and then we applied to a coil with current running through it. This was all connected because of the Biot-Savart Law in finding the field when current is introduced in the system like lines, spheres, and solenoids in which we learned a trick to make it easier to find using number of turns per unit length.

This is the image of a circular current loop in which we used integration because of the many point charges that are interacting in the case or system. And also we saw how it may be applied to a system of a square.

This is the lab set up in which we used the compass which is placed in the middle of the current carrying loop to find the amount of current changes the change in angle of the compass. As a result we placed in the equation of (mew0*I)/(2r)*n which n is the number of the loops the circle contained to find our goal to be close to that of the magnetic field produced by Earth. We find the radius, placing a current on the wires and using the multi-meter to see the amount current being applied and find the value that comes to Earth's field. 

Another view of the experiment of proving or coming close to the actual value of the magnetic field produced by the Earth. There is going to be uncertainty because we were given not the "best" tools to find each of the values to make our result to be precise. There are many things that can taken into account that will give us an uncertainty to our value like the reading of the current, the exact change in angle of the compass or the correct amount of loops going around the circle. However of numbers were close to that actual value and according to the tools that wee being used it was good enough for the experiment unlike the real world situations.

Another image of the experiment from the images above of the set up that uses the equation from the magnetic field of a current element and moving it algebraically to find what we want and eliminating the constants that are not needed to complete our objective.  

This the image of the graph we got were from the experiment above by conducting four trials of changing the current and the angle. As seen in the graph our magnetic fields from each trial were close to the approximate value of Earth's magnetic field of 2.5*10^-5 and used our values to make a graph. The line is almost linear but it has more of an exponential growth to it according to our linear fit of the graph and got the equation of y=29094x-.023 with R^2 value of 0.939.  

The image show that of a coil spread out and connected to an energy source to provide it with a current and using a probe with logger pro to see what is going on with field within the coil. After placing the probe in different parts of the coil and saw that the field is greater when placed in the middle and when it was placed in the ends was a lower value in the coil which sees the interaction of the current in the coils. Among the experiments we were introduce Biot Savart Law and learned a trick of finding the field of an infinite solenoid.