What is Nonelectrical Energy

Chapter Nonelectrical energy

Teach Yourself Electricity and Electronics Third Edition Book
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Teach Yourself Electricity and Electronics Third Edition Book

  • Law. If the EMF is doubled, the current is doubled. If the resistance is doubled, the cur-rent is cut in half. This important law of electrical circuit behavior is covered in detail alittle later in this book.It is possible to have an EMF without having any current. This is the case just before a lightning bolt occurs, and before you touch that radiator after walking on thecarpet. It is also true between the two wires of an electric lamp when the switch isturned off. It is true of a dry cell when there is nothing connected to it. There is no cur-rent, but a current is possible given a conductive path between the two points. Voltage,or EMF, is sometimes called potential or potential difference for this reason.Even a very large EMF might not drive much current through a conductor or resistance. A good example is your body after walking around on the carpet. Althoughthe voltage seems deadly in terms of numbers (thousands), there are not that manycoulombs of charge that can accumulate on an object the size of your body. Thereforein relative terms, not that many electrons flow through your finger when you touch aradiator so you don’t get a severe shock.Conversely, if there are plenty of coulombs available, a small voltage, such as 117volts (or even less), can result in a lethal flow of current. This is why it is so dangerousto repair an electrical device with the power on. The power plant will pump an unlim-ited number of coulombs of charge through your body if you are foolish enough to getcaught in that kind of situation.Nonelectrical energyIn electricity and electronics, there are many kinds of phenomena that involveother forms of energy besides electrical energy.Visible light is an example. A light bulb converts electricity into radiant energy thatyou can see. This was one of the major motivations for people like Thomas Edison towork with electricity. Visible light can also be converted into electric current or voltage.A photovoltaic cell does this.Light bulbs always give off some heat, as well as visible light. Incandescent lampsactually give off more energy as heat than as light. And you are certainly acquaintedwith electric heaters, designed for the purpose of changing electricity into heat energy.This “heat” is actually a form of radiant energy called infrared. It is similar to visiblelight, except that the waves are longer and you can’t see them.Electricity can be converted into other radiant-energy forms, such as radio waves,ultraviolet, and X rays. This is done by things like radio transmitters, sunlamps, andX-ray tubes.Fast-moving protons, neutrons, electrons, and atomic nuclei are an important formof energy, especially in deep space where they are known as cosmic radiation. The en-ergy from these particles is sometimes sufficient to split atoms apart. This effect makesit possible to build an atomic reactor whose energy can be used to generate electricity.Unfortunately, this form of energy, called nuclear energy, creates dangerous by-products that are hard to dispose of.When a conductor is moved in a magnetic field, electric current flows in that conductor. In this way, mechanical energy is converted into electricity. This is how a18 Basic physical concepts