Solar cycle dependence of quiet-time magnetospheric currents
... night side (e.g., Hughes, 1995). Furthermore a magnetospheric ring current circles the Earth, aligned with the geomagnetic equatorial plane. Large-scale field-aligned currents connect the various magnetospheric currents with the high-latitude ionosphere (e.g., McPherron, 1995). If vector field measu ...
... night side (e.g., Hughes, 1995). Furthermore a magnetospheric ring current circles the Earth, aligned with the geomagnetic equatorial plane. Large-scale field-aligned currents connect the various magnetospheric currents with the high-latitude ionosphere (e.g., McPherron, 1995). If vector field measu ...
Induced EMF
... opposite the plastic holder will be a south pole and have field lines directed toward it. Turn up the voltage on the power supply until the current is 0.80 A. Use the compass to verify that the magnetic field at the end of the electromagnet opposite the plastic holder is indeed directed toward this ...
... opposite the plastic holder will be a south pole and have field lines directed toward it. Turn up the voltage on the power supply until the current is 0.80 A. Use the compass to verify that the magnetic field at the end of the electromagnet opposite the plastic holder is indeed directed toward this ...
Gizmos Magnetism Student Exploration Guide
... 2. Observe: Repeat the experiment with iron. What effect does iron have on the filings? _________________________________________________________________________ _________________________________________________________________________ ...
... 2. Observe: Repeat the experiment with iron. What effect does iron have on the filings? _________________________________________________________________________ _________________________________________________________________________ ...
Superconductivity
Superconductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic fields occurring in certain materials when cooled below a characteristic critical temperature. It was discovered by Dutch physicist Heike Kamerlingh Onnes on April 8, 1911 in Leiden. Like ferromagnetism and atomic spectral lines, superconductivity is a quantum mechanical phenomenon. It is characterized by the Meissner effect, the complete ejection of magnetic field lines from the interior of the superconductor as it transitions into the superconducting state. The occurrence of the Meissner effect indicates that superconductivity cannot be understood simply as the idealization of perfect conductivity in classical physics.The electrical resistivity of a metallic conductor decreases gradually as temperature is lowered. In ordinary conductors, such as copper or silver, this decrease is limited by impurities and other defects. Even near absolute zero, a real sample of a normal conductor shows some resistance. In a superconductor, the resistance drops abruptly to zero when the material is cooled below its critical temperature. An electric current flowing through a loop of superconducting wire can persist indefinitely with no power source.In 1986, it was discovered that some cuprate-perovskite ceramic materials have a critical temperature above 90 K (−183 °C). Such a high transition temperature is theoretically impossible for a conventional superconductor, leading the materials to be termed high-temperature superconductors. Liquid nitrogen boils at 77 K, and superconduction at higher temperatures than this facilitates many experiments and applications that are less practical at lower temperatures.