Google Books is a service from Google Inc. that searches the full text of books and magazines that Google has scanned, converted to text using optical character recognition, stored in its digital database. Books are provided either by publishers and authors, through the Google Books Partner Program, or by Google's library partners, through the Library Project. Additionally, Google has partnered with a number of magazine publishers to digitize their archives; the Publisher Program was first known as Google Print when it was introduced at the Frankfurt Book Fair in October 2004. The Google Books Library Project, which scans works in the collections of library partners and adds them to the digital inventory, was announced in December 2004; the Google Books initiative has been hailed for its potential to offer unprecedented access to what may become the largest online body of human knowledge and promoting the democratization of knowledge. However, it has been criticized for potential copyright violations, lack of editing to correct the many errors introduced into the scanned texts by the OCR process.
As of October 2015, the number of scanned book titles was over 25 million, but the scanning process has slowed down in American academic libraries. Google estimated in 2010 that there were about 130 million distinct titles in the world, stated that it intended to scan all of them. Results from Google Books show up in both the universal Google Search and in the dedicated Google Books search website. In response to search queries, Google Books allows users to view full pages from books in which the search terms appear if the book is out of copyright or if the copyright owner has given permission. If Google believes the book is still under copyright, a user sees "snippets" of text around the queried search terms. All instances of the search terms in the book text appear with a yellow highlight; the four access levels used on Google Books are: Full view: Books in the public domain are available for "full view" and can be downloaded for free. In-print books acquired through the Partner Program are available for full view if the publisher has given permission, although this is rare.
Preview: For in-print books where permission has been granted, the number of viewable pages is limited to a "preview" set by a variety of access restrictions and security measures, some based on user-tracking. The publisher can set the percentage of the book available for preview. Users are restricted from downloading or printing book previews. A watermark reading "Copyrighted material" appears at the bottom of pages. All books acquired through the Partner Program are available for preview. Snippet view: A'snippet view' – two to three lines of text surrounding the queried search term – is displayed in cases where Google does not have permission of the copyright owner to display a preview; this could be because Google can not identify the owner declined permission. If a search term appears many times in a book, Google displays no more than three snippets, thus preventing the user from viewing too much of the book. Google does not display any snippets for certain reference books, such as dictionaries, where the display of snippets can harm the market for the work.
Google maintains. No preview: Google displays search results for books that have not been digitized; as these books have not been scanned, their text is not searchable and only the metadata such as the title, publisher, number of pages, ISBN, subject and copyright information, in some cases, a table of contents and book summary is available. In effect, this is similar to an online library card catalog. In response to criticism from groups such as the American Association of Publishers and the Authors Guild, Google announced an opt-out policy in August 2005, through which copyright owners could provide a list of titles that it did not want scanned, Google would respect the request. Google stated that it would not scan any in-copyright books between August and 1 November 2005, to provide the owners with the opportunity to decide which books to exclude from the Project. Thus, Google provides a copyright owner with three choices with respect to any work: It can participate in the Partner Program to make a book available for preview or full view, in which case it would share revenue derived from the display of pages from the work in response to user queries.
It can let Google scan the book under the Library Project and display snippets in response to user queries. It can opt out of the Library Project. If the book has been scanned, Google will reset its access level as'No preview'. Most scanned works are commercially available. In addition to procuring books from libraries, Google obtains books from its publisher partners, through the "Partner Program" – designed to help publishers and authors promote their books. Publishers and authors submit either a digital copy of their book in EPUB or PDF format, or a print copy to Google, made available on Google Books for preview; the publisher can control the percentage of the book available for preview, with the minimum being 20%. They can choose to make the book viewable, allow users to download a PDF copy. Books can be made available for sale on Google Play. Unlike the Library Project, this does not raise any copyright concerns as it is conducted pursuant to an agreement with the publisher; the publisher can choose to withdraw from the agreement at any time.
For many books, Google Books displays the original page numbers. However, Tim Pa
An ampere hour or amp hour is a unit of electric charge, having dimensions of electric current multiplied by time, equal to the charge transferred by a steady current of one ampere flowing for one hour, or 3600 coulombs. The seen milliampere hour is one-thousandth of an ampere hour; the ampere hour is used in measurements of electrochemical systems such as electroplating and for battery capacity where the known nominal voltage is dropped. A milliampere second is a unit of measure used in X-ray imaging, diagnostic imaging, radiation therapy; this quantity is proportional to the total X-ray energy produced by a given X-ray tube operated at a particular voltage. The same total dose can be delivered in different time periods depending on the X-ray tube current. To help express energy, computation over charge values in ampere hour requires precise data of electric tension: in a battery system, for example, accurate calculation of the energy delivered requires integration of the power delivered over the discharge interval.
The battery voltage varies during discharge. The Faraday constant is the charge on one mole of electrons equal to 26.8 ampere hours. It is used in electrochemical calculations also. An AA size dry cell has a capacity of about 2 to 3 ampere hours. Automotive car batteries vary in capacity but a large automobile propelled by an internal combustion engine would have about a 50 ampere hour battery capacity. Since one ampere hour can produce 0.336 grams of aluminium from molten aluminium chloride, producing a ton of aluminium requires transfer of at least 2.98 million ampere hours. Electrochemical equivalent
System of measurement
A system of measurement is a collection of units of measurement and rules relating them to each other. Systems of measurement have been important and defined for the purposes of science and commerce. Systems of measurement in use include the International System of Units, the modern form of the metric system, the imperial system, United States customary units; the French Revolution gave rise to the metric system, this has spread around the world, replacing most customary units of measure. In most systems, length and time are base quantities. Science developments showed that either electric charge or electric current could be added to extend the set of base quantities by which many other metrological units could be defined. Other quantities, such as power and speed, are derived from the base set: for example, speed is distance per unit time. A wide range of units was used for the same type of quantity: in different contexts, length was measured in inches, yards, rods, furlongs, nautical miles, leagues, with conversion factors which were not powers of ten.
Such arrangements were satisfactory in their own contexts. The preference for a more universal and consistent system only spread with the growth of science. Changing a measurement system has substantial financial and cultural costs which must be offset against the advantages to be obtained from using a more rational system; however pressure built up, including from scientists and engineers for conversion to a more rational, internationally consistent, basis of measurement. In antiquity, systems of measurement were defined locally: the different units might be defined independently according to the length of a king's thumb or the size of his foot, the length of stride, the length of arm, or maybe the weight of water in a keg of specific size itself defined in hands and knuckles; the unifying characteristic is. Cubits and strides gave way to "customary units" to meet the needs of merchants and scientists. In the metric system and other recent systems, a single basic unit is used for each base quantity.
Secondary units are derived from the basic units by multiplying by powers of ten, i.e. by moving the decimal point. Thus the basic metric unit of length is the metre. Metrication is complete or nearly complete in all countries. US customary units are used in the United States and to some degree in Liberia. Traditional Burmese units of measurement are used in Burma. U. S. units are used in limited contexts in Canada due to the large volume of trade. A number of other jurisdictions have laws mandating or permitting other systems of measurement in some or all contexts, such as the United Kingdom – whose road signage legislation, for instance, only allows distance signs displaying imperial units – or Hong Kong. In the United States, metric units are used universally in science in the military, in industry, but customary units predominate in household use. At retail stores, the liter is a used unit for volume on bottles of beverages, milligrams, rather than grains, are used for medications; some other standard non-SI units are still in international use, such as nautical miles and knots in aviation and shipping.
Metric systems of units have evolved since the adoption of the first well-defined system in France in 1795. During this evolution the use of these systems has spread throughout the world, first to non-English-speaking countries, to English speaking countries. Multiples and submultiples of metric units are related by powers of ten and their names are formed with prefixes; this relationship is compatible with the decimal system of numbers and it contributes to the convenience of metric units. In the early metric system there were the metre for length and the gram for mass; the other units of length and mass, all units of area and derived units such as density were derived from these two base units. Mesures usuelles were a system of measurement introduced as a compromise between the metric system and traditional measurements, it was used in France from 1812 to 1839. A number of variations on the metric system have been in use; these include gravitational systems, the centimetre–gram–second systems useful in science, the metre–tonne–second system once used in the USSR and the metre–kilogram–second system.
The current international standard metric system is the International System of Units It is an mks system based on the metre and second as well as the kelvin, ampere and mole. The SI includes two classes of units which are agreed internationally; the first of these classes includes the seven SI base units for length, time, electric current, luminous intensity and amount of substance. The second class consists of the SI derived units; these derived. All other quantities are expressed in terms of SI derived units. Both imperial units and US customary units derive from earlier English units. Imperial units were used in the former British Empire and
International System of Units
The International System of Units is the modern form of the metric system, is the most used system of measurement. It comprises a coherent system of units of measurement built on seven base units, which are the ampere, second, kilogram, mole, a set of twenty prefixes to the unit names and unit symbols that may be used when specifying multiples and fractions of the units; the system specifies names for 22 derived units, such as lumen and watt, for other common physical quantities. The base units are derived from invariant constants of nature, such as the speed of light in vacuum and the triple point of water, which can be observed and measured with great accuracy, one physical artefact; the artefact is the international prototype kilogram, certified in 1889, consisting of a cylinder of platinum-iridium, which nominally has the same mass as one litre of water at the freezing point. Its stability has been a matter of significant concern, culminating in a revision of the definition of the base units in terms of constants of nature, scheduled to be put into effect on 20 May 2019.
Derived units may be defined in terms of other derived units. They are adopted to facilitate measurement of diverse quantities; the SI is intended to be an evolving system. The most recent derived unit, the katal, was defined in 1999; the reliability of the SI depends not only on the precise measurement of standards for the base units in terms of various physical constants of nature, but on precise definition of those constants. The set of underlying constants is modified as more stable constants are found, or may be more measured. For example, in 1983 the metre was redefined as the distance that light propagates in vacuum in a given fraction of a second, thus making the value of the speed of light in terms of the defined units exact; the motivation for the development of the SI was the diversity of units that had sprung up within the centimetre–gram–second systems and the lack of coordination between the various disciplines that used them. The General Conference on Weights and Measures, established by the Metre Convention of 1875, brought together many international organisations to establish the definitions and standards of a new system and standardise the rules for writing and presenting measurements.
The system was published in 1960 as a result of an initiative that began in 1948. It is based on the metre–kilogram–second system of units rather than any variant of the CGS. Since the SI has been adopted by all countries except the United States and Myanmar; the International System of Units consists of a set of base units, derived units, a set of decimal-based multipliers that are used as prefixes. The units, excluding prefixed units, form a coherent system of units, based on a system of quantities in such a way that the equations between the numerical values expressed in coherent units have the same form, including numerical factors, as the corresponding equations between the quantities. For example, 1 N = 1 kg × 1 m/s2 says that one newton is the force required to accelerate a mass of one kilogram at one metre per second squared, as related through the principle of coherence to the equation relating the corresponding quantities: F = m × a. Derived units apply to derived quantities, which may by definition be expressed in terms of base quantities, thus are not independent.
Other useful derived quantities can be specified in terms of the SI base and derived units that have no named units in the SI system, such as acceleration, defined in SI units as m/s2. The SI base units are the building blocks of the system and all the other units are derived from them; when Maxwell first introduced the concept of a coherent system, he identified three quantities that could be used as base units: mass and time. Giorgi identified the need for an electrical base unit, for which the unit of electric current was chosen for SI. Another three base units were added later; the early metric systems defined a unit of weight as a base unit, while the SI defines an analogous unit of mass. In everyday use, these are interchangeable, but in scientific contexts the difference matters. Mass the inertial mass, represents a quantity of matter, it relates the acceleration of a body to the applied force via Newton's law, F = m × a: force equals mass times acceleration. A force of 1 N applied to a mass of 1 kg will accelerate it at 1 m/s2.
This is true whether the object is floating in space or in a gravity field e.g. at the Earth's surface. Weight is the force exerted on a body by a gravitational field, hence its weight depends on the strength of the gravitational field. Weight of a 1 kg mass at the Earth's surface is m × g. Since the acceleration due to gravity is local and varies by location and altitude on the Earth, weight is unsuitable for precision
The ampere shortened to "amp", is the base unit of electric current in the International System of Units. It is named after André-Marie Ampère, French mathematician and physicist, considered the father of electrodynamics; the International System of Units defines the ampere in terms of other base units by measuring the electromagnetic force between electrical conductors carrying electric current. The earlier CGS measurement system had two different definitions of current, one the same as the SI's and the other using electric charge as the base unit, with the unit of charge defined by measuring the force between two charged metal plates; the ampere was defined as one coulomb of charge per second. In SI, the unit of charge, the coulomb, is defined as the charge carried by one ampere during one second. New definitions, in terms of invariant constants of nature the elementary charge, will take effect on 20 May 2019. SI defines ampere as follows: The ampere is that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, placed one metre apart in vacuum, would produce between these conductors a force equal to 2×10−7 newtons per metre of length.
Ampère's force law states that there is an attractive or repulsive force between two parallel wires carrying an electric current. This force is used in the formal definition of the ampere; the SI unit of charge, the coulomb, "is the quantity of electricity carried in 1 second by a current of 1 ampere". Conversely, a current of one ampere is one coulomb of charge going past a given point per second: 1 A = 1 C s. In general, charge Q is determined by steady current I flowing. Constant and average current are expressed in amperes and the charge accumulated, or passed through a circuit over a period of time is expressed in coulombs; the relation of the ampere to the coulomb is the same as that of the watt to the joule. The ampere was defined as one tenth of the unit of electric current in the centimetre–gram–second system of units; that unit, now known as the abampere, was defined as the amount of current that generates a force of two dynes per centimetre of length between two wires one centimetre apart.
The size of the unit was chosen so that the units derived from it in the MKSA system would be conveniently sized. The "international ampere" was an early realization of the ampere, defined as the current that would deposit 0.001118 grams of silver per second from a silver nitrate solution. More accurate measurements revealed that this current is 0.99985 A. Since power is defined as the product of current and voltage, the ampere can alternatively be expressed in terms of the other units using the relationship I=P/V, thus 1 ampere equals 1 W/V. Current can be measured by a multimeter, a device that can measure electrical voltage and resistance; the standard ampere is most realized using a Kibble balance, but is in practice maintained via Ohm's law from the units of electromotive force and resistance, the volt and the ohm, since the latter two can be tied to physical phenomena that are easy to reproduce, the Josephson junction and the quantum Hall effect, respectively. At present, techniques to establish the realization of an ampere have a relative uncertainty of a few parts in 107, involve realizations of the watt, the ohm and the volt.
Rather than a definition in terms of the force between two current-carrying wires, it has been proposed that the ampere should be defined in terms of the rate of flow of elementary charges. Since a coulomb is equal to 6.2415093×1018 elementary charges, one ampere is equivalent to 6.2415093×1018 elementary charges moving past a boundary in one second. The proposed change would define 1 A as being the current in the direction of flow of a particular number of elementary charges per second. In 2005, the International Committee for Weights and Measures agreed to study the proposed change; the new definition was discussed at the 25th General Conference on Weights and Measures in 2014 but for the time being was not adopted. The current drawn by typical constant-voltage energy distribution systems is dictated by the power consumed by the system and the operating voltage. For this reason the examples given below are grouped by voltage level. Current notebook CPUs: up to 15...45 A Current high-end CPUs: up to 55...120 A Hearing aid: 700 µA USB charging adapter: 2 A A typical motor vehicle has a 12 V battery.
The various accessories that are powered by the battery might include: Instrument panel light: 166 mA Headlight: 5 A Starter motor on a smaller car: 50 A to 200 A Most Canada and United States domestic power suppliers run at 120 V. Household circuit breakers provide a maximum of 15 A or 20 A of current to a given set of outlets. USB charging adapter: 83 mA 22-inch/56-centimeter portable television: 290 mA Tungsten light bulb: 500–830 mA Toaster, kettle: 12.5 A Hair dryer: 15 A Most European domestic power supplies run at 230 V, most Commonwealth domestic power supplies run at 2
An alkaline battery is a type of primary battery which derives its energy from the reaction between zinc metal and manganese dioxide. Compared with zinc-carbon batteries of the Leclanché cell or zinc chloride types, alkaline batteries have a higher energy density and longer shelf-life, with the same voltage; the alkaline battery gets its name because it has an alkaline electrolyte of potassium hydroxide, instead of the acidic ammonium chloride or zinc chloride electrolyte of the zinc-carbon batteries. Other battery systems use alkaline electrolytes, but they use different active materials for the electrodes. Alkaline batteries account for 80% of manufactured batteries in the US and over 10 billion individual units produced worldwide. In Japan alkaline batteries account for 46% of all primary battery sales. In Switzerland alkaline batteries account for 68%, in the UK 60% and in the EU 47% of all battery sales including secondary types. Alkaline batteries contain Manganese dioxide, which can be toxic in higher concentrations.
However, compared to other battery types, the toxicity of alkaline batteries is moderate. Alkaline batteries are used in many household items such as MP3 players, CD players, digital cameras, toys and radios. Batteries with alkaline electrolyte were first developed by Waldemar Jungner in 1899, working independently, Thomas Edison in 1901; the modern alkaline dry battery using the zinc/manganese dioxide chemistry was invented by Canadian engineer Lewis Urry in the 1950s while working for Union Carbide's Eveready Battery division in Cleveland, OH, building on earlier work by Edison. On October 9, 1957, Karl Kordesch, P. A. Marsal filed US patent for the alkaline battery, it was assigned to the Union Carbide Corporation. When introduced in the late 1960s, alkaline batteries contained a small amount of toxic mercury amalgam to control side reactions at the zinc anode. With mercury content reduced by law and improvements in the purity and consistency of materials, manufacturers have reduced the mercury content in modern cells.
In an alkaline battery, the negative electrode is zinc and the positive electrode is manganese dioxide. The alkaline electrolyte of potassium hydroxide is not part of the reaction, only the zinc and MnO2 are consumed during discharge; the alkaline electrolyte of potassium hydroxide remains, as there are equal amounts of OH− consumed and produced. The half-reactions are: Zn + 2OH− → ZnO + H2O + 2e− 2MnO2 + H2O + 2e− → Mn2O3 + 2OH− Overall reaction: Zn + 2MnO2 ⇌ ZnO + Mn2O3 The chemical energy is stored in the zinc metal, whose cohesive free energy per atom is at least 225 kJ/mol higher than that of the three oxides. Capacity of an alkaline battery is greater than an equal size Leclanché cell or zinc chloride cell because the manganese dioxide is purer and denser, space taken up by internal components such as electrodes is less. An alkaline cell can provide between five times capacity; the capacity of an alkaline battery is dependent on the load. An AA-sized alkaline battery might have an effective capacity of 3000 mAh at low drain, but at a load of 1 ampere, common for digital cameras, the capacity could be as little as 700 mAh.
The voltage of the battery declines during use, so the total usable capacity depends on the cut-off voltage of the application. Unlike Leclanché cells, the alkaline cell delivers about as much capacity on intermittent or continuous light loads. On a heavy load, capacity is reduced on continuous discharge compared with intermittent discharge, but the reduction is less than for Leclanche cells; the nominal voltage of a fresh alkaline cell as established by manufacturer standards is 1.5 V. The effective zero-load voltage of a non discharged alkaline battery, varies from 1.50 to 1.65 V, depending on the purity of the manganese dioxide used and the contents of zinc oxide in the electrolyte. The average voltage under load depends on level of discharge and the amount of current being drawn, varying from 1.1 to 1.3 V. The discharged cell will still have a remaining voltage in the range of 0.8 to 1.0 V. Multiple voltages may be achieved with series of cells; the amount of current an alkaline battery can deliver is proportional to its physical size.
This is a result of decreasing internal resistance as the internal surface area of the cell increases. A rule of thumb is. Larger cells, such as C and D cells, can deliver more current. Applications requiring currents of several amperes, such as powerful flashlights and portable stereos, will require D-sized cells to handle the increased load. Alkaline batteries are manufactured in standardized cylindrical forms interchangeable with zinc-carbon batteries, in button forms. Several individual cells may be interconnected to form a true "battery", such as those sold for use with flashlights and the 9 volt transistor-radio battery. A cylindrical cell is contained in a drawn stainless steel can, the cathode connection; the positive electrode mixture is a compressed paste of manganese dioxide with carbon powder added for increased conductivity. The paste deposited as pre-molded rings; the hollow center of the cathode is lined with a separator, which prevents contact of the electrode materials and short-circuiting of the cell.
The separator is made of a non-woven layer of a synthetic polymer. The separator must conduct ions and remain stable in the al