![Composite Medium with Simultaneously Negative Permeability and](http://s1.studyres.com/store/data/002744098_1-7826a949cb6945251e3c1b9e2dfde0da-300x300.png)
current electricity
... number of electrons travelling in any direction will be equal to the number of electrons travelling in the opposite direction. So, there will be no net electric current. Let us now see what happens to such a piece of conductor if an electric field is applied. To focus our thoughts, imagine the condu ...
... number of electrons travelling in any direction will be equal to the number of electrons travelling in the opposite direction. So, there will be no net electric current. Let us now see what happens to such a piece of conductor if an electric field is applied. To focus our thoughts, imagine the condu ...
Magnetism
... a volcano has produced many lava flows over a past period, scientists can analyze the magnetizations of the various flows and from them get an idea on how the direction of the local Earth's field varied in the past. Surprisingly, this procedure suggested that times existed when the magnetization had ...
... a volcano has produced many lava flows over a past period, scientists can analyze the magnetizations of the various flows and from them get an idea on how the direction of the local Earth's field varied in the past. Surprisingly, this procedure suggested that times existed when the magnetization had ...
Optics, Electricity and Magnetism
... 1.2.1 Introduction: The deviations in the size, shape, position and colour in the actual images produced by a lens in comparison to the object are called aberrations produced by a lens. Chromatic aberrations are distortions of the image due to the dispersion of light in the lenses of an optical syst ...
... 1.2.1 Introduction: The deviations in the size, shape, position and colour in the actual images produced by a lens in comparison to the object are called aberrations produced by a lens. Chromatic aberrations are distortions of the image due to the dispersion of light in the lenses of an optical syst ...
EC331.Sheet1 - Arab Academy for Science, Technology
... 13. What unit is used to represent the level of a diode forward current IF? a) pA b) nA c) A d) mA 14. Which of the following ratings is true? a) Si diodes have higher PIV and narrower temperature ranges than Ge diodes. b) Si diodes have higher PIV and wider temperature ranges than Ge diodes. c) Si ...
... 13. What unit is used to represent the level of a diode forward current IF? a) pA b) nA c) A d) mA 14. Which of the following ratings is true? a) Si diodes have higher PIV and narrower temperature ranges than Ge diodes. b) Si diodes have higher PIV and wider temperature ranges than Ge diodes. c) Si ...
Magnetic field, Biot-Savart, etc - Rose
... Since div B = 0 and in general div (curl F) = 0, we can imagine B to be generated by a vector potential B=xA The vector potential A will of course depend on the currents J which create B. A also has the freedom to have the gradient of any scalar added to it because it won't change B: B = x [(A(J) ...
... Since div B = 0 and in general div (curl F) = 0, we can imagine B to be generated by a vector potential B=xA The vector potential A will of course depend on the currents J which create B. A also has the freedom to have the gradient of any scalar added to it because it won't change B: B = x [(A(J) ...
Superconductivity
![](https://commons.wikimedia.org/wiki/Special:FilePath/Meissner_effect_p1390048.jpg?width=300)
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.