Electromagnetic devices

Transformers are electromagnetic devices that allow electrical power supplied at one potential to be transformed into electrical power at another potential. The potential or voltage may be stepped up (increased) or stepped down (decreased). For instance, in the usual transmission of domestic power, the potential in the transmission lines is greater than the load requirements and a step down transformer is used to reduce the potential at the end use point. 

Mechanically operated screens are vibrated by means of an electromagnetic device as shown in Figure 1.40, or mechanically as shown in Figure 1.41. In the former case the screen itself is vibrated, and in the latter, the whole assembly. Because very rapid accelerations and retardations are produced, the power consumption and the wear on the bearings are high. These screens are sometimes mounted in a multi-deck fashion with... 

Why is an understanding of the transient phenomenon important Large electromagnetic devices such as transformers and motors are practically impervious to the effects of transients. Problems arise because of the sensitivity of the microelectronic devices and circuits that make up the control elements of the power system. The microprocess controller is the nerve center of every present-day manufacturing or commercial facility. Medical electronic instruments used in healthcare facilities are becoming more sophisticated and at the same time increasingly susceptible to... 

For the drop technique, the isoperibolic calorimeters are most frequently used. The calorimetric device consists of two main parts a furnace and a heated block. Between the calorimetric block and the furnace, there is a system of shields controlled by a mechanic, hydraulic or electromagnetic device, which prevents the heat transfer from the furnace to the calorimetric block. The calorimeter is made of copper with a cavity closed by a shield. A resistance thermometer wound on the block measures its temperature. Such a calorimeter can work up to 1700°C, especially when the furnace... 

Now, let us concentrate on the mode of propulsion of the movable mirror in various Fourier spectrometers. Among the discussed 13 instruments, there are three spectrometers (for the far-infrared ) where the movable mirror is driven by a synchronous motor (No. 1, 3, and 5c in Table 3) and where the speed of the mirror can be varied from 1 to 25 m/sec. These are the socalled "slow-scan instruments. They employ a slow Golay-detector (cf. Table 2), and the radiation of the source is chopped at a certain frequency as was pointed out already in context with the optical diagram (cf. Fig. 49). In the other ten instruments listed in Table 3 (No. 2a, b, 4a—e, 5a, b, and 6), the movable mirror is driven by an electromagnetic device like a linear motor and where the speed can be varied... 

Mixed metal oxides derived from Fe203 and of general formula M Fe 2C>4 or M Fe - 02 are commonly known as ferrites despite the absence of discrete oxoanions. They include compounds of commercial importance by virtue of their magnetic properties, e.g. electromagnetic devices for information storage for discussion of the magnetic properties of mixed metal oxides, see Chapter 27. Spinel and... 

Transformer - An electromagnetic device that changes the voltage of alternating current electricity. It consists of an induction coil having a primary and secondary winding and a closed iron core. 

S.R.H. Hoole. Computer-Aided Analysis and Design of Electromagnetic Devices. Elsevier, New York, 1989. While the title wouldn t make you think so, this is an excellent introductory text on the use of numerical techniques to solve boundary value problems in electrodynamics. The text also contains sections on mesh generation and solution methods. Furthermore, it provides pseudocode for most of the algorithms discussed throughout the text. 

Manganese-zinc ferrites (Zn Mni jcFe204) and nickel-zinc ferrites are industrially important magnetic materials. The former are used when constructing the cores of intermediate-frequency transformers, inductors, loudspeakers and other electromagnetic devices, while the latter have found application in the modern electronics industry, due primarily to their high electrical resistivity. 

Hoshino Y, Kuroda R, Nagamune K, Yagi M, Mizuno K, Yamaguchi M, Muratsu H, Yoshiya S, Kurosaka M (2007) In vivo measurement of the pivot-shift test in the anterior cruciate ligament-deficient knee using an electromagnetic device. Am J Sports Med 35 1098-1104... 

Proximity Sensor An electromagnetic device that senses the presence or absence of a component through its effect on a magnetic field in the sensing unit. 

One finds the handiwork of electrical engineers in such mundane devices as thermostats to the ubiquitous Internet, where everything from the network cards to the keyboards, screens, and software are crafted by electrical engineers. Electrical engineers are historically involved with electromagnetic devices as well, such as the electrical starter of a car or the turbines of a hydroelectric plant. Many devices that aid artists, such as sound recording and electronic musical instruments, are also the inspiration of electrical engineers. 

The history of electromagnetic devices provides an excellent example of the complex interplay of fundamental and applied science. The phenomena... 

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