4.P.1 Explain how various forces affect the motion
... Depending on how many of the electric charges in them are free to move, materials show great differences in how much they respond to electric forces. At one extreme, an electrically insulating material such as glass or rubber does not ordinarily allow any passage of charges through it. At the other ...
... Depending on how many of the electric charges in them are free to move, materials show great differences in how much they respond to electric forces. At one extreme, an electrically insulating material such as glass or rubber does not ordinarily allow any passage of charges through it. At the other ...
... It is clear that, for example, the function corresponding to the zeroth eigenvalue of the operator HP with p = 1 and satisfying the condition (13) has one zero, since dwP /dz with p = 1 has no zeroes in the open interval (0, a). It is easy to verify that the index p determines the number of zeroes p ...
Section_18_Toroidal_..
... that the pressure is constant along the direction of B . Conversely, the field lines of B must lie in constant pressure surfaces, i.e., they must wrap around a cylindrical surface. Since J p 0 also, the current must also lie in these surfaces. However, it need not be aligned with B ; if there ...
... that the pressure is constant along the direction of B . Conversely, the field lines of B must lie in constant pressure surfaces, i.e., they must wrap around a cylindrical surface. Since J p 0 also, the current must also lie in these surfaces. However, it need not be aligned with B ; if there ...
Physics, Chapter 32: Electromagnetic Induction
... this induced current was due to the change in the magnetic field around the secondary circuit. As long as the current in the primary circuit remained constant, the magnetic field around both P and S remained constant, but the galvanometer read zero during this time. But when the magnetic field was a ...
... this induced current was due to the change in the magnetic field around the secondary circuit. As long as the current in the primary circuit remained constant, the magnetic field around both P and S remained constant, but the galvanometer read zero during this time. But when the magnetic field was a ...
Current Electricity (AQA Unit 1)
... Oscilloscopes are used to display the time variations of electrical signals. Any physical quantity that can be converted into a suitable electrical signal can be displayed on an oscilloscope. An oscilloscope is a device that is used to display and measure electrical oscillations. The oscilloscope co ...
... Oscilloscopes are used to display the time variations of electrical signals. Any physical quantity that can be converted into a suitable electrical signal can be displayed on an oscilloscope. An oscilloscope is a device that is used to display and measure electrical oscillations. The oscilloscope co ...
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.