Obtaining and analyzing magnetic hysteresis loops: an insertion of students in magnetism research

An experimental apparatus for obtaining magnetic hysteresis curves was built, with the participation of undergraduate physics students, aiming at a visualization of the fundamentals that characterize the magnetic response of ferromagnetic materials subjected to alternating magnetic fields. Hysteresis loops of the secondary core of a transformer were obtained, visualizing them on the screen of an oscilloscope in the graphic form of voltage in a capacitor connected to the secondary winding as a function of the voltage measured in a resistor connected to the primary. Loops were obtained for five values of voltage applied to the primary of the transformer in the range of 160–220 V. An increase in coercive, remanent and maximum magnetization fields was observed with increasing primary voltage. The relative magnetic permeability curves show a maximum close to the coercive field values, and thus the non-linearity of the permeability with the magnetic field intensity was observed. Finally, with increasing voltage, the students estimated the power lost in 5 hysteresis curves associated with the rotation of magnetic dipoles and dynamic factors.

Keywords
Teaching Physics; Experiment; Magnetism; Magnetic Hysteresis