| 单词 | potential difference |
| 例句 | Obama’s book is the highlight of publishing’s holiday season and for some independent bookstores the potential difference between remaining in business or closing down. Barack Obama memoir off to record-setting start in sales 2020-11-18T05:00:00Z It was 11 imps for Milner, not 12, and the potential difference could have been 22, not 23. Bridge: Bridge Players Tom and Carol Sanders 2012-08-31T21:58:58Z More than 40% of athletes included were female so that potential differences in recovery between males and females could be explored. College athletes experience worse post-injury outcomes for concussions suffered outside of sports 2023-09-20T04:00:00Z But they are aiming to carry out a larger study and investigate the potential differences in brain health between male and female athletes in contact sports. Concussion: Wales rugby great JPR Williams' fear after study 2023-07-26T04:00:00Z In 2017, she and the company signed an agreement that stated any potential differences involving the two parties would be arbitrated rather than litigated before courts. Woman claimed Kobe Bryant promised her stake in investment. Now she owes Vanessa $1.5 million 2023-06-28T04:00:00Z Recent comments by French President Emmanuel Macron have highlighted potential differences between Europe and the United States on China. G7 to discuss 'common and concerted' approach to China, U.S. official says 2023-04-16T04:00:00Z Figure 19.5 A typical electron gun accelerates electrons using a potential difference between two metal plates. College Physics for AP Courses 2015-08-12T00:00:00Z A voltmeter in the external circuit allows measurement of the potential difference between the two half-cells. Chemistry 2019-02-14T00:00:00Z The authors also did not factor in potential differences in demographic and socioeconomic factors. How one unvaccinated, unmasked teacher spread coronavirus to students and parents 2021-08-27T04:00:00Z Careful to cultivate an image of a unified party, the White House has taken pains to conduct significant outreach to Democrats to understand their interests and smooth out potential differences, one aide said. On infrastructure, lofty ideas are colliding with congressional reality 2021-04-18T04:00:00Z "It was a place where race, religion, and social class did not matter. Everyone was there for one cause. The sense of unity in that place transcended any potential differences." Egypt's revolution: 'The roar of the crowd shook my feet' 2021-02-10T05:00:00Z An electron accelerated through a potential difference of 1 V is given an energy of 1 eV. College Physics for AP Courses 2015-08-12T00:00:00Z They believe World Athletics disregarded what they say are potential differences in body proportions between elite Black runners and other populations. Paralympian Blake Leeper, ruled ineligible for Olympics, says he’s ‘baffled’ by the decision 2020-10-27T04:00:00Z An early study, not yet peer-reviewed, of two cities in China suggested the potential difference. Social distancing could buy U.S. valuable time against coronavirus 2020-03-10T04:00:00Z Therefore, resolving potential differences between what the essay calls “multiple interactions” might prove difficult. How new Army-developed AI technology can save infantry in a firefight 2019-12-03T05:00:00Z "We had to train hospital staff to collect these data. We hope that the numbers will be big enough to detect potential differences." First malaria vaccine rolled out in Africa—despite limited efficacy and nagging safety concerns 2019-11-26T05:00:00Z The separation of charge creates a potential difference of 70 to 90 mV across the cell membrane. College Physics for AP Courses 2015-08-12T00:00:00Z “We teach and live a compassionate and loving response towards all people regardless of any potential differences of opinion,” the school said in a statement. Teachers quit in protest over what they consider anti-gay policy at Christian school in Shoreline 2019-09-09T04:00:00Z The potential difference between these two strongly polarized regions creates enormous voltage, internal discharges and flow of current. Analysis | ‘Never seen anything like it’: How a ‘near constant’ lightning show lit up parts of central Maryland on Sunday night 2019-08-19T04:00:00Z Instead, Knight said, the best indicator is how an organization is set up to handle potential differences, or to turn them into a collaborative strength. ‘Hi, I’m Tom Brady’: How the Patriots' 41-year-old quarterback relates to teammates 2019-01-12T05:00:00Z When the team used a battery to apply a potential difference of three volts to the ion-soaked graphene layers, the stack became opaque to infrared. How to fool infrared vision gear into thinking you are not there 2018-07-05T04:00:00Z The values of currents and electric potential differences in an electric circuit are determined by the properties and arrangement of the individual circuit elements such as sources of emf, resistors, and capacitors. College Physics for AP Courses 2015-08-12T00:00:00Z The study wasn’t big enough to detect any potential differences in patient survival. Warming, not cooling, donated livers may improve transplants 2018-04-18T04:00:00Z In fact, when it comes to potential differences in intelligence between groups, one of the remarkable dimensions of the human genome is how little genetic variation there is. The unwelcome revival of ‘race science’ 2018-03-02T05:00:00Z This synthetic system generated a potential difference of 110 volts. Electric Eel-Inspired Devices Could Power Artificial Human Organs 2017-12-15T05:00:00Z Instead, thousands of cells called electrocytes are arranged along its body, each producing a small ion gradient and therefore a potential difference across them. An electric-eel-inspired soft power source from stacked hydrogels 2017-12-12T05:00:00Z Electromotive force is directly related to the source of potential difference, such as the particular combination of chemicals in a battery. College Physics for AP Courses 2015-08-12T00:00:00Z Clint Dempsey had been touted as the potential difference this year, having missed last year’s play-offs with his heart ailment, but like most of his team-mates he had few opportunities to stall the Toronto momentum. Jozy Altidore has last laugh to seal MLS Cup glory for Toronto FC 2017-12-09T05:00:00Z That energy is then stored in the field between the pencil and the earth; it is the gravitational potential difference between the pencil on the ground and in its new position. A Letter to My High School Physics Teacher 2017-06-05T04:00:00Z Mr. Mnuchin’s comments on the distribution of the tax burden also show a potential difference with Republicans in the House, who are developing their own tax plan to lower rates and limit tax breaks. Trump’s Treasury Choice Says ‘No Absolute Tax Cut’ for the Wealthy 2016-11-30T05:00:00Z Vrana considered gaining weight and getting stronger this offseason as the potential difference between being ready to join the Washington Capitals and spending another season with their American Hockey League affiliate in Hershey. To compete for a roster spot, Jakub Vrana had to weigh his options 2016-09-30T04:00:00Z Why are the chemicals able to produce a unique potential difference? College Physics for AP Courses 2015-08-12T00:00:00Z Ideally we would be able to set up an experiment to understand potential differences before an encounter. Roland Fryer Answers Reader Questions About His Police Force Study 2016-07-12T04:00:00Z But only when we are infinitely separated from all we know do we hold our maximum potential difference, our maximum ability to do work, our maximum opportunity to move the world. A Letter to My High School Physics Teacher 2017-06-05T04:00:00Z They plan to monitor the effects using brain imaging to look at potential differences in both the structure and function of certain brain regions. Science Shows How Distracting Things Like Cell Phones Can Make You Poor Parents 2016-01-06T05:00:00Z An email to Unilever asking about potential difference in pricing or added functionality of the “Men’s Ultimate” version of the product was not answered. Why is #MasculinitySoFragile? 2015-09-23T04:00:00Z Recall that emf is the potential difference of a source when no current is flowing. College Physics for AP Courses 2015-08-12T00:00:00Z “Increasing women’s participation in clinical research studies is an important goal, but we also seek to encourage researchers to analyze and report their data to understand potential differences between men and women,” Dr. Cook said. Barbra Streisand rallies women against heart disease, decries gender ‘injustice’ in research 2015-07-12T04:00:00Z Sam Gregg of the Acton Institute, a faith-based group that works to promote free markets, said the leak will focus attention on potential differences between the draft text and the actual encyclical. Pope Francis blasts global warming deniers in leaked draft of encyclical 2015-06-15T04:00:00Z Those investigations might start with potential differences in the way men and women process alcohol. How Much Alcohol Is Too Much? 2015-05-26T04:00:00Z When asked about potential differences at a house party Wednesday night, he joked that he is smarter and better looking before moving on. Jeb Bush, seeking more distance from his brother, offers some rare criticism 2015-05-21T04:00:00Z When such a battery moves charge, it puts the charge through a potential difference of 12.0 V, and the charge is given a change in potential energy equal to ΔPE = qΔV . College Physics for AP Courses 2015-08-12T00:00:00Z It’s one trillion times the amount of energy an electron acquires when it moves between two electrodes with a one-volt potential difference between them. Things To Know As The Large Hadron Collider Breaks Energy Records 2015-05-21T04:00:00Z The opportunity to play on the same stage as the public schools, not the potential differences in standards, is what Twaddell found most notable from Tuesday’s ruling. ‘Tebow Bill’ passes Va. Senate, opening playing field for home-school athletes 2015-02-18T05:00:00Z In addition to the heavy erasures, an initial investigation found potential differences in handwriting on short-answer questions, the memo said. Changed answers on Beacon Hill school tests raise alert 2014-10-25T04:00:00Z In a neuronal circuit, information is transmitted through neurons in the form of an action potential, which is the electric potential difference between the inside and the outside of a neuron. [Perspective] Silencing Neurons with Light 2014-04-29T14:56:15.053Z So to find the energy output, we multiply the charge moved by the potential difference. College Physics for AP Courses 2015-08-12T00:00:00Z To study potential differences in behavior among the mice, the experimenters used a measure called “roaming entropy.” Where Does Identity Come From? 2013-05-28T14:45:05.400Z Then they could be giving up an NFL-ready potential difference maker for a second round pick in a so-so draft. Dan Pompei's Bears mailbag 2013-04-22T23:03:00Z It remains to be seen how and when the smaller but vocal Yammer community integrates with the much larger SharePoint community as there are some potential differences of opinion. These are the Top 25 Microsoft SharePoint Influencers for 2012 2012-11-08T23:39:43Z But in humans, CALB1 is expressed only in the dentate gyrus, pointing to a potential difference between the brains of these other mammals and ours. Five Surprises From Billionaire Paul Allen's Mind Map 2012-09-19T17:46:45Z Which term is more descriptive, voltage or potential difference? College Physics for AP Courses 2015-08-12T00:00:00Z Second, he would accompany this with an explicit set of social policies – and here the potential differences are profound – that addresses the need for equitable burden-sharing. Winner of US election will have limited economic options 2012-08-02T12:00:01Z The striking distance increases faster than the potential difference. Popular scientific lectures 2012-04-24T02:00:17.273Z This induction coil is capable of yielding currents of enormous potential differences, alternating with extreme rapidity. The inventions, researches and writings of Nikola Tesla With special reference to his work in polyphase currents and high potential lighting 2012-03-28T02:00:22.660Z The advantage in using compressed air round the spark gap is that we can increase the effective potential difference between the balls without rendering the spark non-oscillatory. Hertzian Wave Wireless Telegraphy 2012-01-09T03:00:20.570Z More precisely, what is the relationship between potential difference and electric potential energy? College Physics for AP Courses 2015-08-12T00:00:00Z There must be a steadily maintained electric pressure, known under different aspects as “electromotive force,” “potential difference,” or “voltage.” Hawkins Electrical Guide, Number One Questions, Answers, & Illustrations, A Progressive Course of Study for Engineers, Electricians, Students and Those Desiring to acquire a Working Knowledge of Electricity and its Applications 2011-12-24T03:07:54.823Z So let’s dissect business model and value capture potential differences between the dot-com boom and what is going on with the social network companies right now. So, Is There Another Tech Bubble Or Not? 2011-12-08T23:51:54Z It is necessary to insulate the ends or terminals of the secondary heavily with hard rubber, because even dry wood is by far too poor an insulator for these currents of enormous potential differences. The inventions, researches and writings of Nikola Tesla With special reference to his work in polyphase currents and high potential lighting 2012-03-28T02:00:22.660Z The current through this ball coherer is, therefore, a logarithmic function of the potential difference between its ends, of the form and exhibits no discontinuity. Hertzian Wave Wireless Telegraphy 2012-01-09T03:00:20.570Z Effectively, the membranes are thus charged capacitors with important functions related to the potential difference across the membrane. College Physics for AP Courses 2015-08-12T00:00:00Z The study tried to account for potential differences in educational background and other issues between military families and the general population that might skew the results. Study in Wash. state suggests more violence among kids of combat veterans, including daughters 2011-10-31T09:00:46Z The resistance R is defined as the ratio of the applied potential difference V to the current I produced, i.e. The New Gresham Encyclopedia Volume 4, Part 2: Ebert to Estremadura 2011-04-14T02:00:56.200Z But unfortunately one is limited by the obtainable potential difference. The inventions, researches and writings of Nikola Tesla With special reference to his work in polyphase currents and high potential lighting 2012-03-28T02:00:22.660Z It is essential that this generator should be able to create not only large potential difference, but also a certain minimum electric current. Hertzian Wave Wireless Telegraphy 2012-01-09T03:00:20.570Z If the plates are held at a fixed potential difference ΔV, sketch the path of both a positively charged object placed between the near ends, and a negatively charged object placed near the open ends. College Physics for AP Courses 2015-08-12T00:00:00Z We arbitrarily call the potential of the earth zero, since all potential difference is relative and there is no absolute potential any more than absolute level. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z These solenoids, by means of a suitable mechanism, act in opposition, the current solenoid separating the carbons, and the potential difference solenoid bringing them closer together. The New Gresham Encyclopedia Volume 4, Part 2: Ebert to Estremadura 2011-04-14T02:00:56.200Z It is perfectly practicable, with very great potential differences in the gap, to dissipate several horse-power in the arc of the discharge without even noticing a small increase in the temperature of the electrodes. The inventions, researches and writings of Nikola Tesla With special reference to his work in polyphase currents and high potential lighting 2012-03-28T02:00:22.660Z The current densities and potential differences frequently used for some of the commoner metals are given in the following table, taken from M’Millan’s Treatise on Electrometallurgy. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 2 "Ehud" to "Electroscope" 2011-01-29T03:00:23.777Z All such devices create a potential difference and are loosely referred to as voltage sources. College Physics for AP Courses 2015-08-12T00:00:00Z In the absolute determination of capacity we have to measure the ratio of the charge of a condenser to its plate potential difference. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z This may be done automatically by the action of a pair of solenoids, one carrying the current which passes through the arc, the other carrying a current proportional to the potential difference across the arc. The New Gresham Encyclopedia Volume 4, Part 2: Ebert to Estremadura 2011-04-14T02:00:56.200Z The potential difference, however, at the ends of the filaments is very great and might be possibly 20,000 volts or more, if the filaments were straight and their ends far apart. The inventions, researches and writings of Nikola Tesla With special reference to his work in polyphase currents and high potential lighting 2012-03-28T02:00:22.660Z Quadrant electrometers have also been designed especially for measuring extremely small potential differences. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 2 "Ehud" to "Electroscope" 2011-01-29T03:00:23.777Z When a voltage source is connected to a conductor, it applies a potential difference V that creates an electric field. College Physics for AP Courses 2015-08-12T00:00:00Z In the case of lead and lead dioxide, this potential difference is just over two volts per cell. Einstein and car batteries: A spark of genius 2011-01-13T10:39:10Z This instrument, the development of which is due chiefly to Lord Kelvin, is capable of making accurate measurements of electrostatic potential differences down to quite low values. The New Gresham Encyclopedia Volume 4, Part 2: Ebert to Estremadura 2011-04-14T02:00:56.200Z A coil made in this manner and with care is capable of withstanding enormous potential differences. The inventions, researches and writings of Nikola Tesla With special reference to his work in polyphase currents and high potential lighting 2012-03-28T02:00:22.660Z Throughout a wide range the deflections are proportional to the potential difference producing them. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 2 "Ehud" to "Electroscope" 2011-01-29T03:00:23.777Z Figure 20.20 The potential difference V between the terminals of an AC voltage source fluctuates as shown. College Physics for AP Courses 2015-08-12T00:00:00Z Metallic tin is not electropositive enough compared with the electronegativity of its oxide to deliver a useful potential difference. Einstein and car batteries: A spark of genius 2011-01-13T10:39:10Z “There’s a potential difference of opinion of how many will be needed.” This Land: Campus Visit by Obama Isn?t Simple 2010-09-29T00:47:00Z I attribute this to the greater specific inductive capacity of the glass, in consequence of which, with the same potential difference, a greater amount of energy is taken up in it than in rubber. The inventions, researches and writings of Nikola Tesla With special reference to his work in polyphase currents and high potential lighting 2012-03-28T02:00:22.660Z Observation of θ with measurement of the value of l and r reckoned in centimetres and W in grammes gives us the potential difference of the balls in absolute C.G.S. or electrostatic units. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 2 "Ehud" to "Electroscope" 2011-01-29T03:00:23.777Z In this chapter several series and parallel combinations of resistors are discussed and their effects on currents and potential differences are analyzed. College Physics for AP Courses 2015-08-12T00:00:00Z The lower interest rates are in Japan, the bigger the potential difference between rates in the nation and elsewhere, giving market players more incentive to sell the yen to invest in other currencies. Pressed to Act, Bank of Japan Sees Few Ways to Lift Demand 2010-08-23T13:17:00Z The resistance R was about 9 ohms, and the potential difference E was varied from three to six Clark cells, giving a rate of heat-supply about 2 to 6 watts. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 1 "Calhoun" to "Camoens" In observing the behavior of gases, and the luminous phenomena obtained, the importance of the electrostatic effects was noted and it appeared desirable to produce enormous potential differences, alternating with extreme rapidity. The inventions, researches and writings of Nikola Tesla With special reference to his work in polyphase currents and high potential lighting 2012-03-28T02:00:22.660Z When the instrument is to be used to determine the potential difference between two conductors, they are connected to the two opposite pairs of quadrants. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 2 "Ehud" to "Electroscope" 2011-01-29T03:00:23.777Z Kirchoff’s rules are used to calculate currents and potential differences in circuits that combine resistors in series and parallel, and resistors and capacitors. College Physics for AP Courses 2015-08-12T00:00:00Z This maximum current is called the saturation current and the value of the potential difference required to give this maximum current is called the saturation P.D. or saturation voltage. A Brief Account of Radio-activity Self-registering voltmeters indicate at any moment the potential difference in every tank, and therefore give notice of short circuits occurring at any part of the installation. Encyclopaedia Britannica, 11th Edition, Volume 7, Slice 3 "Convention" to "Copyright" In passing the oscillating discharges through the primary of a specially constructed coil, it is easy to obtain enormous potential differences with only few turns of the secondary. The inventions, researches and writings of Nikola Tesla With special reference to his work in polyphase currents and high potential lighting 2012-03-28T02:00:22.660Z Varley discovered the interesting fact that no current could be sent through the rarefied gas unless a certain minimum potential difference of the electrodes was excited. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 2 "Ehud" to "Electroscope" 2011-01-29T03:00:23.777Z How would you go about calculating the potential difference? College Physics for AP Courses 2015-08-12T00:00:00Z We shall discuss later the causes of the rise in the current with large potential differences, when we consider ionization by collision. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 8 "Conduction, Electric" An induction coil in an alternating circuit for changing potential difference, such as high alternating voltage into low direct current voltage. Electricity for Boys In this experiment the potential difference at the terminals of the lamps varies in sign theoretically three to four million times a second. The inventions, researches and writings of Nikola Tesla With special reference to his work in polyphase currents and high potential lighting 2012-03-28T02:00:22.660Z A sharp tap was now given to the stalk, and a sudden diminution, or negative variation, of current occurred, the resting potential difference being decreased by ·026 volt. Response in the Living and Non-Living The familiar term voltage is the common name for potential difference. College Physics for AP Courses 2015-08-12T00:00:00Z If, however, the potential difference changes sign before the negative ions reach CD, these ions will go back to AB. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 8 "Conduction, Electric" The action simply develops potential difference, and this generates the current where a circuit exists. Scientific American Supplement, No. 711, August 17, 1889 But since the effect likewise depends on the frequency, it maybe properly stated that it depends on the time rate of the variation of the potential difference. The inventions, researches and writings of Nikola Tesla With special reference to his work in polyphase currents and high potential lighting 2012-03-28T02:00:22.660Z The potential difference depends on the condition of the plant, and the season in which it may have been gathered. Response in the Living and Non-Living Keep in mind that whenever a voltage is quoted, it is understood to be the potential difference between two points. College Physics for AP Courses 2015-08-12T00:00:00Z Perhaps the simplest of these consists in determining the relation between the current passing between two parallel plates immersed in ionized gas and the potential difference between the plates. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 8 "Conduction, Electric" Consequently an insulator, or an open-circuited conductor, traversing a field, consumes no energy, potential difference only being produced. Scientific American Supplement, No. 711, August 17, 1889 The rapidity of the interruptions of the current with a magnet depends on the intensity of the magnetic field and on the potential difference at the end of the arc. The inventions, researches and writings of Nikola Tesla With special reference to his work in polyphase currents and high potential lighting 2012-03-28T02:00:22.660Z Experiments with High Tension Alternating Currents.—Sparking distance of arc formed by a potential difference of 20,000 volts.—1 illustration. Scientific American Supplement, No. 810, July 11, 1891 For example, every battery has two terminals, and its voltage is the potential difference between them. College Physics for AP Courses 2015-08-12T00:00:00Z At higher pressures the current rises far above these values and increases rapidly with the potential difference. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 8 "Conduction, Electric" The object of this is to continue the record in snowstorms, &c., when the potential difference of air and earth is very great. Scott's Last Expedition Volume I The reason is that the secondary of this coil is wound for low tension, having only 150 turns, and the potential difference at the terminals of the lamp is therefore small. The inventions, researches and writings of Nikola Tesla With special reference to his work in polyphase currents and high potential lighting 2012-03-28T02:00:22.660Z Edison found that under the worst conditions with a wet and salted track, at a potential difference of twenty volts between the two rails, the extreme loss was only two and one-half horse-power. Edison, His Life and Inventions There is a potential difference across the membrane of about –70 mV . College Physics for AP Courses 2015-08-12T00:00:00Z This cathode fall of potential is shown by experiment to be very approximately equal to the minimum potential difference. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 8 "Conduction, Electric" After this accident minute calculations were made and it was ascertained that a potential difference of no less than 100,00 volts existed between the framework of the dirigible and the trees. Aeroplanes and Dirigibles of War Were I to take another coil with many more turns in the secondary, the effect would be increased, since it depends partially on the potential difference, as before remarked. The inventions, researches and writings of Nikola Tesla With special reference to his work in polyphase currents and high potential lighting 2012-03-28T02:00:22.660Z Regulation of the potential difference is managed in various ways. The Project Gutenberg Encyclopedia Volume 1 of 28 All such devices create a potential difference and can supply current if connected to a resistance. College Physics for AP Courses 2015-08-12T00:00:00Z Thus in the cases in which the measurements could be made with the greatest accuracy the agreement between the cathode fall and the minimum potential difference is very close. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 8 "Conduction, Electric" FARAD.—The capacitance of a condenser in which a potential difference of 1 volt causes it to have a charge of 1 coulomb of electricity. The Radio Amateur's Hand Book This field possesses different 'potentials' at its various points and so there exists a certain potential difference between the two electric charges. Man or Matter This is the potential difference between fear and desire, between injury and conjugation. Origin and Nature of Emotions On the small scale, the potential difference creates an electric field that exerts force on charges, causing current. College Physics for AP Courses 2015-08-12T00:00:00Z Let us call this force ap; then if l is the distance of the anode from the negative glow the potential difference between these points will be alp. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 8 "Conduction, Electric" The farad is the capacitance of a condenser in which a potential difference of 1 volt causes it to have a charge of 1 coulomb of electricity. The Radio Amateur's Hand Book Thus by measuring the potential difference between the ends of the two resistances successively, we may compare their resistances. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 8 "Conduction, Electric" If, on the other hand, we can measure the potential difference in some known units, and similarly measure the current flowing, we can determine the resistance of a single electrolyte. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 8 "Conduction, Electric" Emf is not a force at all; it is a special type of potential difference. College Physics for AP Courses 2015-08-12T00:00:00Z In the arc discharge we get very large currents with comparatively small potential differences. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 8 "Conduction, Electric" This potential difference may be measured without passing any appreciable current through the tapping electrodes, and thus the resistance of the liquid deduced. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 8 "Conduction, Electric" The difference between conduction through gases and through metals is shown in a striking way when we use potential differences large enough to produce the saturation current. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 8 "Conduction, Electric" Suppose we have got a potential difference between the plates more than sufficient to produce the saturation current, and let us increase the distance between the plates. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 8 "Conduction, Electric" A parallel connection is used because objects in parallel experience the same potential difference. College Physics for AP Courses 2015-08-12T00:00:00Z The connexion between V, the potential difference between the terminals, and l, the length of the arc, is somewhat analogous to that which holds for the spark discharge. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 8 "Conduction, Electric" Thus when the plates in the preceding example are far apart, it will take a larger potential difference to produce this current than when the plates are close together. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 8 "Conduction, Electric" The plate CD is connected with an alternating current dynamo, which produces a simply-periodic potential difference between AB and CD, the other pole being put to earth. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 8 "Conduction, Electric" The relation between the current and the potential difference when the velocity of the negative ion is much greater than the positive is very easily obtained. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 8 "Conduction, Electric" The potential difference between points b and d is then zero, meaning that b and d are at the same potential. College Physics for AP Courses 2015-08-12T00:00:00Z The potential difference between the terminals is affected by the pressure of the gas. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 8 "Conduction, Electric" Here an increase in the potential difference produces a much greater percentage increase than in conduction through metals, where the current is proportional to the potential difference. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 8 "Conduction, Electric" For the same potential difference the current is proportional to k, the velocity under unit electric force of the ion which carries the current. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 8 "Conduction, Electric" The relation between the current and the potential difference in this case is in accordance with the results of the theory of ionization by collision. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 8 "Conduction, Electric" The emf is the potential difference of a source when no current is flowing. College Physics for AP Courses 2015-08-12T00:00:00Z The nature of the gas also affects the potential difference. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 8 "Conduction, Electric" Thus, for example, if we halve the pressure the same potential difference will produce a spark of twice the length. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 8 "Conduction, Electric" We may regard the part of the discharge between the cathode and the negative glow as a discharge taking place under minimum potential difference through a distance equal to the critical spark length. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 8 "Conduction, Electric" The connexion between the potential difference and the spark length has been made the subject of a large number of experiments. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 8 "Conduction, Electric" The numerical value of the emf depends on the source of potential difference. College Physics for AP Courses 2015-08-12T00:00:00Z When this is the case the back electromotive force is destroyed and the same potential difference will carry a much larger current. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 8 "Conduction, Electric" With sparks of these lengths it was found that it was possible to get a discharge with less than 330 volts, the minimum potential difference in air. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 8 "Conduction, Electric" When the force rises to this value a discharge takes place even though the potential difference is much less than 330 volts; in some of Earhart’s experiments it was only about 2 volts. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 8 "Conduction, Electric" This kind of discharge is determined not by the condition that the potential difference should have a given value, but that the electric force should have a given value. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 8 "Conduction, Electric" This fluid interacts with the Earth’s magnetic field to produce a potential difference between the two river banks. College Physics for AP Courses 2015-08-12T00:00:00Z For let E0 be the electromotive force of the battery, R the resistance of the leads, i the current, the potential difference between the terms in the gas will be E0 − Ri. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 8 "Conduction, Electric" The mercury lamps, however, in which the discharge passes through mercury vapour are luminous with a potential difference of about 12 volts. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 8 "Conduction, Electric" The Arc Discharge.—The discharges we have hitherto considered have been characterized by large potential differences and small currents. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 8 "Conduction, Electric" For a quiet arc an increase in current is accompanied by a fall in potential difference, while for the hissing arc the potential difference is independent of the current. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 8 "Conduction, Electric" The preceding measurements refer to mean potentials, and no conclusions as to the actual potential differences at any time can be drawn when the discharge is discontinuous, unless we know the law of discontinuity. Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 8 "Conduction, Electric" |
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