Physics
Electrical Energy
Electrical energy is the energy produced by the movement of electrons through a conductor. It is a form of kinetic energy that can be harnessed to power various devices and systems. Electrical energy is fundamental to the functioning of modern technology and is generated through processes such as electromagnetic induction and chemical reactions in batteries.
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7 Key excerpts on "Electrical Energy"
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Index pages curate the most relevant extracts from our library of academic textbooks. They’ve been created using an in-house natural language model (NLM), each adding context and meaning to key research topics.
eBook - ePub- Adrian Waygood(Author)
- 2018(Publication Date)
- Routledge(Publisher)
Chapter 15 Energy, work, heat and powerObjectives
On completion of this chapter, you should be able to- define each of the following terms:
- energy
- work
- heat
- power.
- specify the SI unit of measurement for each of the following:
- energy
- work
- heat
- power.
- state the fundamental equation for the work done by an electric circuit.
- state the fundamental equation for the power of an electric circuit.
- derive alternative equations for the work done by, and the power of, an electric circuit.
- define the term ‘efficiency’.
- solve problems on energy, work, power and efficiency.
- explain how electricity supply companies bill their residential consumers.
- read an analogue energy meter.
- summarise the claimed advantages of smart energy meters compared with conventional energy meters.
- describe the relationship between Electrical Energy and heat.
- solve problems on work and heat.
Note : unfortunately, quantities used in thermodynamics share the same symbols as completely different quantities used in electrical engineering. So, in this unit, you should be aware that- in electricity : U = potential difference; Q = electric charge
- in thermodynamics : U = internal energy; Q = heat
Introduction
The study of electricity is really the study of energy and of energy conversion . Unfortunately, the word ‘energy’ , together with the related terms, ‘work’ , ‘heat’ and ‘power’ , have ‘everyday meanings’ and are frequently used interchangeably by the layman. But, for those of us who are studying electrical science, it is important that we understand the scientific meanings of these terms.Energy, work and heat
Energy
The word, ‘energy ’, is derived from the Greek, ‘energeia ’: a word that first appeared as long ago as the fourth century BC in a work by the Greek philosopher, Aristotle. However, it is thought to have been used in its modern sense only since the beginning of the nineteenth century.‘Energy ’ is probably one of the most fundamental concepts in physics, but also one of the hardest to define. In fact, it’s one of those rare scientific terms where it’s very much easier to explain what it does or how it behaves , rather than what it is
eBook - ePubElectrical Engineering
Fundamentals
- Viktor Hacker, Christof Sumereder(Authors)
- 2020(Publication Date)
- De Gruyter Oldenbourg(Publisher)
B have to be fulfilled.Figure 1.17: Superconducting surface.1.11 Energy and electrical power
Electrical Energy is provided by the combination of electric current and electric potential in an electrical circuit. The mechanical workW = ∫is comparable to electrical work done on a charged particle by an electric field.F ⃗⋅ ds ⃗If the force (F ) is used to lift an object by the distance (s), mechanical work is carried out. The object now has higher energy content by that amount (potential energy). This energy can perform work by e.g. letting the object drop.Electric energy the following applies:W = Q ⋅ V = V ⋅ I ⋅ tV Voltage in VI Current in At Time in sQ Electric charge in AsW Electrical work/energy in WsThe electric charge represents the product of current I multiplied by time (Q = I ⋅ t ). Therefore, the following applies:W =⋅ t = P ⋅ tPV ⋅ I⏟P Power in WThe work performed per time unit is called power P.P =W tWith direct current, the electric power P that is transformed in an electric load is the result of the voltage V multiplied by the current I :P = V ⋅ IPower is one of the most important parameters for electrical machines and devices. By insertion of the Ohm’s law, the equation can be transformed to:P = Wor also:Power hyperbola
All V-I pairs of values that lead to the same power, e.g.P = 2 W
eBook - ePubEnergy Storage
A New Approach
- Ralph Zito, Haleh Ardebili(Authors)
- 2019(Publication Date)
- Wiley-Scrivener(Publisher)
The history of the development of physical concepts is not the prime concern here, but some knowledge of their evolution does serve to bring more closely to our attention and scrutiny a better appreciation of terms that we employ daily. Sometimes it is necessary to begin understanding or developing a body of knowledge in order to make certain basic assumptions on an entirely intuitive basis. As scientifically unsatisfying as that may be, it is unavoidable at times. One could draw a weak comparison to plane geometry (Euclid) with regard to its various axioms and the declaration that parallel lines never meet. Even the concept of straight lines is rather intuitive in nature.Perhaps the best definition is that a force is required to change the motion of a body. Many problems arise in finding acceptable definitions for the basic parameters of physical science, namely, the abstract concepts of mass, time, force, and energy. However, we must learn to be satisfied with definitions that leave something to be desired in order to move on toward generating a working body of mechanics that enables us to design and build practical devices that serve our purposes.An interesting definition of energy comes from the Grolier Encyclopedia, which states:Energy can be measured in terms of mechanical work, but because not all forms of energy can be converted into useful work, it is more precise to say that the energy of a system changes by an amount equal to the net work done on the system … In classical physics, energy, like work, is considered a scalar quantity; the units of energy are the same as those of work. These units may be ergs, joules, watt-hours, foot-pounds, or foot-poundals, depending on the system of units being used. In modern science, energy and the three components of linear momentum are thought of as different aspects of a single four-dimensional vector quantity, much as time is considered to be one aspect of the four-dimensional space-time continuum … Energy exists in many different forms. The form that bodies in motion possess is called kinetic energy. Energy may be stored in the form of potential energy, as it is in a compressed spring. Chemical systems possess internal energy, which can be converted by various devices into useful work; for example, a fuel such as gasoline can be burned in an engine to propel a vehicle. Heat energy may be absorbed or released when the internal energy of a system changes while work is done on or by the system. (1993)
eBook - ePub- Bertrand Cassoret(Author)
- 2021(Publication Date)
- CRC Press(Publisher)
1 What Is Energy?The concept of energy is not that simple to approach. Energy is not always visible or palpable. It is hard to quantify. It is not necessarily material, and its existence may even be ignored. Yet, energy is indispensable to life. It is omnipresent in our activities and influences them considerably.1.1 Energy in Rich Countries’ Daily Life
At night, ventilation devices, internet boxes, freezers, refrigerators, alarm clocks, chargers and various electrical devices left on stand-by consume energy permanently. In the morning, electrical power supplies light. Energy, mostly gas, is required to heat up homes.Preparing breakfast or other meals requires the consumption of energy: coffee makers, toasters, ovens, microwaves, hotplates, dishwashers, etc. What about the bathroom? We would not wash so often without abundant energy. You need some to pump water up the water tower, to heat it up and more to make soap.To listen to the radio, we use electrical appliances which receive waves from electrical emitters, relaying the programmes made in studios which are inconceivable without electrical power. Of course, it is the same with television.Telephones are charged with electricity. E-mails and internet data are stored on IT servers which are greedy for electricity. To go to work, most of us need petrol for our cars or electricity for public transport. In almost all workplaces, there are computers, lighting, heating, ventilation, various electrical appliances and even machines and vehicles running on petroleum or gas.Anything we buy requires energy to be produced. For any of the things around us, base ores had to be mined – generally with the use of oil-fuelled machines – and transported. Coal, gas, oil and electricity are used to run the transformation and manufacturing factories, and then, all these products have to be transported too.Anything we eat requires energy. Food is the energy provided to living creatures, but let us not forget about the fuel required by agricultural machinery, the fabrication of fertilizers, the running of food-processing factories, transport systems, etc. We would not eat the same food if fields were ploughed using animal power, if there were no available energy to preserve food or transport it.
eBook - ePub- S. Bobby Rauf(Author)
- 2020(Publication Date)
- CRC Press(Publisher)
The term “electromotive” force stems from the early recognition of electrical current as something that consisted, strictly, of the movement of “electrons.” Nowadays, however, with the more recent breakthroughs in the renewable and non-traditional electrical power generating methods and systems like microbial fuel cells and hydrocarbon fuel cells, electrical power is being harnessed, more and more, in the form of charged particles that may not be electrons. In batteries, such as those used in automobiles, as we will see in the batteries chapter, the flow of current driven by voltage potential difference consists not only of negatively charged electrons, e −, but also types of ions, including H + and HSO 4 − ions. 1 Two, relatively putative, analogies for voltage in the mechanical and civil engineering disciplines are pressure and elevation. In the mechanical realm – or more specifically in the fluid and hydraulic systems – high pressure or pressure differential pushes fluid from one point to another and performs mechanical work. Similarly, voltage – in the form of voltage difference between two points, as with the positive and negative terminals of an automobile battery – moves electrons or charged particles through loads such as motors, coils, resistive elements, wires, or conductors. As electrons or charged particles are pushed through loads like motors, coils, resistive elements, light filaments, etc., Electrical Energy is converted into mechanical energy, heat energy, or light energy. In equipment like rechargeable batteries, during the charging process, applied voltage can push ions from one electrode (or terminal) to another and thereby “charge” the battery
eBook - ePubInstrumentation
An Introduction for Students in the Speech and Hearing Sciences
- T. Newell Decker, Thomas D. Carrell(Authors)
- 2004(Publication Date)
- Psychology Press(Publisher)
Invoking a hydraulic analogy, charge, a quantity of electrons, may be thought of as similar to liters, a quantity of fluid. Similarly, current, a flow of electrons may be considered to be analogous to liters per second.To review, current is defined as the number of total protons or electrons divided by the standard number of protons or electrons in 1 C. Current (I) is defined as the rate of electron flow in coulombs per second and is expressed in amperes.Voltage
Much as the flow of water through a hose is dependent on the pressure or force with which the water is made to flow, electrical current in a conductor depends on the force pushing the free electrons. Force is defined as mass times acceleration. The greater the force, the larger the current. Voltage, which is a measure of force, is analogous to pressure. For a clearer understanding of voltage, take a closer look at several other related concepts. The first of these is work (J ). The usual unit of measure for work is the joule (J). Work is done when a force (F) moves through a distance (D).(1.2) One J equals 1 Newton-meter. In other words, 1 J is the amount of work done when a force of 1 Newton moves a distance of 1 m. A Newton (N ) is a measure of force equal to .225 lbs.The second concept is that of potential energy . A body has potential energy if it can do (has the potential to do) work on another body. Furthermore, the amount of energy a body has equals the work it can do. If a body has 12 J of energy, it can do 12 J of work. Figure 1.6 illustrates these concepts. The figure shows a body that “weighs” 100 Newtons. If it is released from its position in the figure, it will push down with a force of 100 Newtons and move through a distance of 5 m. How much work will be accomplished?The amount of work that this body can do is equal to 500 J. Therefore, this elevated body has a potential energy of 500 J with respect to its position relative to the ground. To put this statement into electrical terms, examine Fig. 1.7
- S. Bobby Rauf(Author)
- 2021(Publication Date)
- River Publishers(Publisher)
Chapter 1 Electrical Engineering Basics and Direct CurrentIntroduction
In this chapter, we will explore the basics of electrical engineering terms, concepts, principles, and analytical techniques. Many readers who embark on investing time and effort in studying this text are likely to do so for the key purpose of gaining an introduction into the field of electricity. Many others, on the other hand, might be interested in refurbishing prior knowledge of electrical engineering terms, concepts, principles, and basic analytical techniques. Regardless of whether you belong to one of these two groups —or are simply in pursuit of electrical engineering at the intermediate or associate degree level — in this chapter we will lay the foundations in the electrical engineering realm by covering basic electrical engineering terms, concepts, and principles, without the understanding of which, discussion and study of terms that bear important practical significance, such as power factor, real power, reactive power, apparent power, load factor, etc. would not be feasible.Most of the material in this chapter pertains to DC, or Direct Current, electricity. However, some entities we will discuss in this chapter, such as capacitive reactance, inductive reactance, and impedance are fundamentally premised in the AC, Alternating Current, realm.Electrical engineering is largely rooted in the field of physics. Physics, and electrical engineering, as most other fields in science, depend on empirical proof of principles and theories. Empirical analysis and verification require measurement tools or instrumentation. So, after gaining a better understanding of the basic electrical concepts, we will conclude this chapter with an introduction to two of the most common and basic electrical instruments, i.e., multi-meter and clamp-on ammeter.
