Physics 30 Lesson 18 Electric Current
... Italian scientist who designed the first electrochemical cell. An electrochemical cell is one in which a spontaneous chemical reaction produces electrical energy. Volta’s cell was the first to produce a steady flow of electric current. Until his discovery, all electrical experiments used electrostat ...
... Italian scientist who designed the first electrochemical cell. An electrochemical cell is one in which a spontaneous chemical reaction produces electrical energy. Volta’s cell was the first to produce a steady flow of electric current. Until his discovery, all electrical experiments used electrostat ...
P3.8.1.2
... A tube diode consists of a hermetically sealed, evacuated glass bulb containing two electrodes: a thermionic cathode that emits electrons and an anode (see Fig. 1). If a suitable voltage is applied between the cathode and the anode, there will be an electric current between the two poles. The cathod ...
... A tube diode consists of a hermetically sealed, evacuated glass bulb containing two electrodes: a thermionic cathode that emits electrons and an anode (see Fig. 1). If a suitable voltage is applied between the cathode and the anode, there will be an electric current between the two poles. The cathod ...
Power Electronic Devices - University of Washington
... • During the conduction period, the voltage drop across the solid-state device is about one volt. This voltage drop multiplied by the current inside the device produces losses. • When the device is in the blocking mode (open), a small amount of leakage current flows inside the device which also prod ...
... • During the conduction period, the voltage drop across the solid-state device is about one volt. This voltage drop multiplied by the current inside the device produces losses. • When the device is in the blocking mode (open), a small amount of leakage current flows inside the device which also prod ...
Cathode ray oscilloscope
... (h) a mumetal screen which surrounds the tube and shields it from stray magnetic fields. The focusing and accelerating systems are connected at different points along a resistor chain. Focusing is achieved by varying the voltage applied between the two anodes A1 and A2. Since secondary electrons are ...
... (h) a mumetal screen which surrounds the tube and shields it from stray magnetic fields. The focusing and accelerating systems are connected at different points along a resistor chain. Focusing is achieved by varying the voltage applied between the two anodes A1 and A2. Since secondary electrons are ...
Active Physics: Electricity
... Light bulbs operate because they complete the circuit. They are also an example of a resistor. They produce light by heating a tungsten filament. The friction that causes the glow comes from the flow of electrons in the metal. Electrons flow like water in a hose, each particle moves along as the one ...
... Light bulbs operate because they complete the circuit. They are also an example of a resistor. They produce light by heating a tungsten filament. The friction that causes the glow comes from the flow of electrons in the metal. Electrons flow like water in a hose, each particle moves along as the one ...
Electron Impact Excitation of Helium
... identify the energies that are absorbed most efficiently by the helium. To those ends, we have a helium tube circuit wired as shown in the diagram. • The ~4V filament supply provides current for heating the filament to temperatures required for thermionic emission of electrons. There is a diode (bui ...
... identify the energies that are absorbed most efficiently by the helium. To those ends, we have a helium tube circuit wired as shown in the diagram. • The ~4V filament supply provides current for heating the filament to temperatures required for thermionic emission of electrons. There is a diode (bui ...
Cavity magnetron
The cavity magnetron is a high-powered vacuum tube that generates microwaves using the interaction of a stream of electrons with a magnetic field while moving past a series of open metal cavities (cavity resonators). Bunches of electrons passing by the openings to the cavities excite radio wave oscillations in the cavity, much as a guitar's strings excite sound in its sound box. The frequency of the microwaves produced, the resonant frequency, is determined by the cavities' physical dimensions. Unlike other microwave tubes, such as the klystron and traveling-wave tube (TWT), the magnetron cannot function as an amplifier, increasing the power of an applied microwave signal, it serves solely as an oscillator, generating a microwave signal from direct current power supplied to the tube.The first form of magnetron tube, the split-anode magnetron, was invented by Albert Hull in 1920, but it wasn't capable of high frequencies and was little used. Similar devices were experimented with by many teams through the 1920s and 30s. On November 27, 1935, Hans Erich Hollmann applied for a patent for the first multiple cavities magnetron, which he received on July 12, 1938, but the more stable klystron was preferred for most German radars during World War II. The cavity magnetron tube was later improved by John Randall and Harry Boot in 1940 at the University of Birmingham, England. The high power of pulses from their device made centimeter-band radar practical for the Allies of World War II, with shorter wavelength radars allowing detection of smaller objects from smaller antennas. The compact cavity magnetron tube drastically reduced the size of radar sets so that they could be installed in anti-submarine aircraft and escort ships.In the post-war era the magnetron became less widely used in the radar role. This was because the magnetron's output changes from pulse to pulse, both in frequency and phase. This makes the signal unsuitable for pulse-to-pulse comparisons, which is widely used for detecting and removing ""clutter"" from the radar display. The magnetron remains in use in some radars, but has become much more common as a low-cost microwave source for microwave ovens. In this form, approximately one billion magnetrons are in use today.