矿石收音机(国外英文资料).docVIP

矿石收音机(国外英文资料) Crystal receiver Conducting modeling Http:///screencast/introducingwolframalpha.html Http:///bbs/index.php Data interchange for trade Edison effect Also known as thermionic emission effects, Edison discovered in 1883, Make a large number of electronic heating metal which overcome the surface barrier and escape phenomenon. Similar to the gas molecules to metal free electrons as thermal movement rules, there is a certain distribution. The rate on the surface of the metal exists forces block the electron escape, the power required to overcome the resistance of Electronic Plaza, called in the work. At room temperature, only a very small amount of kinetic energy of electrons over work, very little from the electronic metal surface escape. Generally when the metal temperature rose to 1000 degrees above, the electric work function of kinetic energy is larger than the number of war drama increase, a large number of electronic escape of a metal, this is the hot electron emission. If there is no external electric field, heat the accumulation of electron escape near the metal surface, a space charge, it will stop the hot electron emission. Usually made of metal wire to emission of hot electrons as cathode, a metal plate as anode, the voltage, the hot electrons in the The electric field moves from the cathode to the anode, thus emitting and flowing continuously to form an electric current. As the voltage increases, the electrons emitted from the cathode reach the anode per unit time, so the current is saturated The cathode of many electronic vacuum devices is operated by thermionic emission. As the thermionic emission depends on the work of the material and its temperature, a cathode with high melting point and low energy is selected In addition to hot electron emission, by electron flow or ion bombarding electrons are emitted from the metal surface, known as the two secondary electron emission, by the strong electric field caused by electron emission is called fi