Expt4 Tech Paper Physics 72.1

Introduction Magnetism plays a large part in our modern world's technology. Magnets are used today to image parts of the body, to explore the mysteries of the human brain, and to store data for computers. Magnetism also allows us to explore the structure of the Universe, the atomic structure of materials, and the quark structure of elementary particles. In order to describe the magnetic interaction associated with a magnet, the concept of a field is introduced. This is similarly done to many closed spaced current carrying loops forming a coil, wherein determining the magnetic field is just similar as with a bar magnet. In doing so, the magnitude and approximate orientation of the Earth’s magnetic field, and the permeability of the core material will also be determined. In this experiment, you will map magnetic fields from different sources and combination sources and measure the strength of the magnetic field produced by loops of wires. Solution During the experiment, the magnetic field is determined. Direct proportionality is observed on the permeability of core material, the current and the number of loops in the solenoid. This is summarized by the equation where B is the magnetic field, is the permeability of the core material, N is the number of loops and I is the current. Moreover, loop density is the number of loop per unit length, and so by inspection, the magnetic field would be directly proportional to loop density (N/L). In order to map magnetic field lines, one must first have the knowledge that magnetic field lines travel from the North to the South Pole. Within the coils of the solenoid, a strong magnetic field arises whenever current runs through the wire. The direction of the magnetic field depends on the direction of the current. Outside the coil, the magnetic field is zero. A solenoid acts in some ways like a permanent magnet but one which can be reversed, and turned on and off at will. By visualizing the magnetic field of two small connected magnets, we determine that when the magnets are connect by North and South pole, it acts as one big bar magnet, which has one North and one South pole. On the other hand, when the bar magnets are connected by same poles, the field would try to repel each other. References: http://ocw.mit.edu/courses/physics/8-02t-electricity-and-magnetism-spring-2005/labs/exp05.pdf