상자기성

소개

Ferromagnetism is the property in which materials exhibit permanent magnetic field under the influence of external magnetic field. It is indeed, one of the most fundamental principles lying under the mechanism of audiotape, videotape, and etc. In order to evaluate the ferromagnetic property of a particular material, we can measure the magnitude of magnetic field exerted by the material under the external magnetic field. This produces a special kind of plot called “magnetic hysteresis”, which can be used to determine the ferromagnetic property of the material

목차

Ⅰ. Introduction
Ⅱ. Theoretical Background
1.Capacitance Integrator
2.Ferromagnetism
3.Experimental Measurement of Ferromagnetic Property of the Material
4.Magnetic Hysteresis

Ⅲ. Experimental Procedure
1.Experiment #1 Capacitance Integrator
2.Experiment #2 Magnetic Hysteresis

Ⅳ. Experiment Results and Analysis
1.Experiment #1 Capacitive Integrator
2.Experiment #2 Magnetic Hysteresis

Ⅴ. Conclusions

본문내용

Ⅱ. Theoretical Background
Capacitance Integrator
below, capacitance integrator is comprised of input voltage, output voltage, capacitance, and resistor.
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We term the input voltage, the voltage that we have given to the circuit. Moreover, we term the output voltage, the magnitude of voltage difference across the capacitor.
The charge accumulated in the capacitor can be calculated by means of the current as the following equation, with denoting the current and denoting the charge.
(1)
We denote the output voltage as which can



For the experiment #1 capacitance integrator, we have sent square waves and ramped up waves of different frequencies and observed how the output voltage corresponded well with the theoretically expected one. Since the output voltage is the integration of the input voltage that we gave, we could observe alternating piece-wise linear curves for the square wave and piece-wise connected parabolic curves for the ramped up waves. If the frequency were increased, we could observe resultant voltage to be more floppy.
For the experiment #2 magnetic hysteresis, we have applied different magnitudes of external magnetic field over pins and nails. Observing hysteresis curve, we could observe that with stronger external magnetic field, the curve became wider with larger remnant magnetization and coercivity indicating that magnetic dipoles aligned more strongly and exhibited stronger ferromagnetic property.
In addition, we observed how the hysteresis curve differed according to the number of pin. We could observe the hysteresis curve expanded with respect to the increasing number of pins, indicating that an overall ferromagnetic property enhanced as the number of pins were increased.
For non-ferromagnetic material, such as paper clips, we could not observe hysteresis curve, but only could find magnetization curve. We could not either find remnant magnetization at all.

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