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For the ray tracing program Dielectric Shader by Mental Ray, see Dielectric Shader . A dielectric, or electrical Insulator , is a substance that is highly resistant to the flow of an Electric Current . Although a Vacuum is also an excellent dielectric, the following discussion applies primarily to physical substances. When a dielectric medium interacts with an applied electric field, charges are redistributed within its atoms or molecules. This redistribution alters the shape of an applied electrical field both inside the dielectric medium and in the region nearby. When two electric charges move through a dielectric medium, the interaction energies and forces between them are reduced. When an Electromagnetic wave travels through a dielectric, both its Speed and its Wavelength decrease, while its frequency remains constant. EXPLANATION APPLICATIONS The use of a dielectric in a Capacitor presents several advantages. The simplest of these is that the conducting plates can be placed very close to one another without risk of contact. Also, if subjected to a very high Electric Field , any substance will Ionize and become a Conductor . Dielectrics are more resistant to ionization than dry Air , so a capacitor containing a dielectric can be subjected to a higher operating Voltage . Layers of dielectric are commonly incorporated in manufactured Capacitor s to provide higher capacitance in a smaller space than capacitors using only Air or a Vacuum between their plates, and the term ''dielectric'' refers to this application as well as the insulation used in power and RF cables. SOME PRACTICAL DIELECTRICS Dielectric materials can be solids, liquids, or gases. In addition, a high vacuum can also be a useful, lossless dielectric even though its relative dielectric constant is only unity. Solid dielectrics are perhaps the most commonly used dielectrics in electrical engineering, and many solids are very good insulators. Some examples include Porcelain , Glass , and most Plastic s. Air, Nitrogen and Sulfur Hexafluoride are the three most commonly used gaseous dielectrics.
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