 Methods of producing electricity In this learning activity, you'll review the six different ways in which electricity is produced, chemical, friction, heat, light, magnetism, and pressure. Let's click on the pictures below for a detailed description of each method. Chemical Metals inserted into chemicals cause a reaction that transfers electrons to produce an electrical charge. Batteries operate this way. The chemical is called an electrolyte. An example of an electrolyte is one that combines hydrochloric acid with water. When copper is inserted into the electrolyte, as shown here, electrons transfer from the metal into the solution. Since copper loses electrons, it has a positive charge. When zinc is inserted into the electrolyte, electrons transfer from the solution to the metal. Since zinc gains electrons, it becomes negatively charged. One end of the copper bar is the positive terminal, and one end of the zinc bar is the negative terminal of the battery. Friction Static charges are probably the best example of producing electricity by friction. A static charge occurs when certain materials are rubbed together and electrons are transferred from one object to another. The materials used to produce the charge determine the type of charge that develops. When a rubber rod is rubbed by a wool cloth, electrons are removed from the wool and deposited on the rod. The rod becomes negatively charged because it has an excess of electrons. If a glass rod is rubbed by the wool, electrons are removed from the glass and deposited on the wool. The rod becomes positively charged because it has a deficiency of electrons. A static electricity charge can only be built up on insulator materials because they keep electrons stationary and do not allow them to move to a different location. Heat Some materials readily give up electrons, and some materials accept electrons. Copper and zinc are examples of metals that have this property. When they are joined together, electrons will leave the copper atom and enter the zinc atoms. Therefore, the copper becomes positively charged since it has a deficiency of electrons, and the zinc becomes negatively charged because it has a surplus of electrons. The charge across both metals is proportional to the temperature to which they are exposed. Since the temperature is increased, more energy is provided to release more electrons and create a higher voltage. A practical example of this type of device is the thermal couple. It is used to measure temperature. Its voltage is applied to a voltmeter that has a scale which reads temperature instead of voltage. Light A light beam consists of particles called photons. When the photons strike the surface of a plate made from some materials such as potassium, sodium, or lithium, electrons from their atoms are released. The electrons travel to an adjacent plate made of some other type of material. The material that loses electrons becomes positively charged, and the material that gains electrons becomes negatively charged. Terminals are connected to these plates, as shown here, to provide a voltage to external devices that use DC electrical power. This method of light-activated power is called the photovoltaic process. Magnetism When a conductor such as a copper coil is moved through a magnetic field created by a magnet, the force from the flux lines of the magnet cause valence electrons to be dislodged from the copper atoms. The direction that the electrons move through the wire is determined by the direction that the coil moves relative to the magnet. Electricity that is produced by generators uses this method. Pressure When pressure is applied to some types of materials such as a crystal, the force of that pressure causes the electrons to be dislodged from some of its atoms. The diagram here shows a crystal before pressure is applied. The material has no charge. At the right, pressure is applied. It causes the electrons to leave one side of the material and accumulate on the other side. Thus, positive and negative charges are built up on opposite sides. Then the pressure is released. The electrons return to their orbits and the material becomes uncharged. The size of the charge is proportional to the pressure applied. The name given to the effective pressure causing electric charges is piezoelectricity. The word piezo is derived from the Greek word meaning pressure. Piezo crystals have been used for phonograph pickup. As the needle rides through the grooves of the record, the crystal bends and produces a varying voltage that is amplified as it drives a speaker. This concludes this learning activity. Methods of producing electricity.