METHODS OF PRODUCING VOLTAGE (ELECTRICITY) Basic Electrical TheoryWhen the force is removed, the material is decompressed and immediately causes an electricforce in the opposite direction. The power capacity of these materials is extremely small.However, these materials are very useful because of their extreme sensitivity to changes ofmechanical force.Example: One example is the crystal phonograph cartridge that contains a Rochelle saltFigure 14 Pressure Applied to Certain Crystals Produces an Electric Chargecrystal. A phonograph needle is attached to the crystal. As the needle moves inthe grooves of a record, it swings from side to side, applying compression anddecompression to the crystal. This mechanical motion applied to the crystalgenerates a voltage signal that is used to reproduce sound.ThermoelectricitySome materials readily give up their electrons and others readily accept electrons. For example,when two dissimilar metals like copper and zinc are joined together, a transfer of electrons cantake place. Electrons will leave the copper atoms and enter the zinc atoms. The zinc gets asurplus of electrons and becomes negatively charged. The copper loses electrons and takes ona positive charge. This creates a voltage potential across the junction of the two metals. Theheat energy of normal room temperature is enough to make them release and gain electrons,causing a measurable voltage potential. As more heat energy is applied to the junction, moreelectrons are released, and the voltage potential becomes greater, as shown in Figure 15. Whenheat is removed and the junction cools, the charges will dissipate and the voltage potential willdecrease. This process is called thermoelectricity. A device like this is generally referred to asa "thermocouple."ES-01 Page 22 Rev. 0
Integrated Publishing, Inc. - A (SDVOSB) Service Disabled Veteran Owned Small Business