In response to an external magnetic field, the domains may grow to millimeter size, aligning themselves as shown in Figure 2(b). Domains are small and randomly oriented in an unmagnetized ferromagnetic object. Within domains, the poles of individual atoms are aligned. The regions within the material called domains act like small bar magnets. (This results in the attraction of the previously unmagnetized material to the magnet.) What happens on a microscopic scale is illustrated in Figure 2. When a magnet is brought near a previously unmagnetized ferromagnetic material, it causes local magnetization of the material with unlike poles closest, as in Figure 1. Note that there are attractive forces between the magnets. The iron becomes a permanent magnet with the poles aligned as shown: its south pole is adjacent to the north pole of the original magnet, and its north pole is adjacent to the south pole of the original magnet. An unmagnetized piece of iron is placed between two magnets, heated, and then cooled, or simply tapped when cold. Not only do ferromagnetic materials respond strongly to magnets (the way iron is attracted to magnets), they can also be magnetized themselves-that is, they can be induced to be magnetic or made into permanent magnets. Other materials exhibit weak magnetic effects, which are detectable only with sensitive instruments. A group of materials made from the alloys of the rare earth elements are also used as strong and permanent magnets a popular one is neodymium. Such materials are called ferromagnetic, after the Latin word for iron, ferrum. Only certain materials, such as iron, cobalt, nickel, and gadolinium, exhibit strong magnetic effects. Describe the relationship between electricity and magnetism.Explain the significance of the Curie temperature.Describe the role of magnetic domains in magnetization.Variable power and remote control are available.Īdams does not stock rectifiers but offers them through special order. Most rectifiers incorporate a provision for reverse current that ensures positive release of even those alloy steels which are magnetically retentive. Release is a function of the rectifier and not the magnet. Whether used in manual or automated handling of ferrous parts, they must release the work as readily as they attract and hold. The rectifier can be mounted on the magnet, and be operated by remote control. A rectifier is required to release the electromagnet from the surface on which it is applied. Smaller magnets can operate on 12 volts DC larger magnets may require 115 or 220 VDC. Variable power sources and remote control are available. Typically the applied voltage is Direct Current (DC), but in some cases, Alternating Current (AC) can be used. Round and Rectangular Flat-Faced ElectromagnetsĮlectromagnets require direct current power in order to generate a magnetic field.
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