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15-515: The Indian locomotive class WAM-1 was a class of 25 kV AC electric locomotives that was developed in the late 1950s by the Groupement 50Hz ( a consortium of European locomotive manufacturers) for Indian Railways . The model name stands for broad gauge (W) , AC Current (A), Mixed traffic (M) locomotive, 1st generation (1). They entered service in 1960 thus making them India's first AC electric locomotive . A total of 100 WAM-1 were built by

30-427: A battery is determined by the chemistry of that cell (see Galvanic cell § Cell voltage ). Cells can be combined in series for multiples of that voltage, or additional circuitry added to adjust the voltage to a different level. Mechanical generators can usually be constructed to any voltage in a range of feasibility. Nominal voltages of familiar sources: In 1800, as the result of a professional disagreement over

45-441: A ratio because the cgs unit of voltage is inconveniently small and one volt in this definition is approximately the emf of a Daniell cell , the standard source of voltage in the telegraph systems of the day. At that time, the volt was defined as the potential difference [i.e., what is nowadays called the "voltage (difference)"] across a conductor when a current of one ampere dissipates one watt of power. The "international volt"

60-533: A series-connected array of several thousand or tens of thousands of junctions , excited by microwave signals between 10 and 80 GHz (depending on the array design). Empirically, several experiments have shown that the method is independent of device design, material, measurement setup, etc., and no correction terms are required in a practical implementation. In the water-flow analogy , sometimes used to explain electric circuits by comparing them with water-filled pipes, voltage (difference in electric potential)

75-414: Is also equivalent to electronvolts per elementary charge : The volt is named after Alessandro Volta . As with every SI unit named for a person, its symbol starts with an upper case letter (V), but when written in full, it follows the rules for capitalisation of a common noun ; i.e., volt becomes capitalised at the beginning of a sentence and in titles but is otherwise in lower case. Historically

90-606: Is likened to difference in water pressure , while current is proportional to the amount of water flowing. A resistor would be a reduced diameter somewhere in the piping or something akin to a radiator offering resistance to flow. The relationship between voltage and current is defined (in ohmic devices like resistors ) by Ohm's law . Ohm's Law is analogous to the Hagen–Poiseuille equation , as both are linear models relating flux and potential in their respective systems. The voltage produced by each electrochemical cell in

105-578: Is the elementary charge and h is the Planck constant ), a "conventional" value K J-90 = 0.4835979 GHz/μV was used for the purpose of defining the volt. As a consequence of the 2019 revision of the SI , as of 2019 the Josephson constant has an exact value of K J = 483 597 .848 416 98 ... GHz/V , which replaced the conventional value K J-90 . This standard is typically realized using

120-435: Is the potential difference between two points that will impart one joule of energy per coulomb of charge that passes through it. It can be expressed in terms of SI base units ( m , kg , s , and A ) as It can also be expressed as amperes times ohms (current times resistance, Ohm's law ), webers per second (magnetic flux per time), watts per ampere (power per current), or joules per coulomb (energy per charge), which

135-496: The " conventional " volt, V 90 , defined in 1987 by the 18th General Conference on Weights and Measures and in use from 1990 to 2019, was implemented using the Josephson effect for exact frequency-to-voltage conversion, combined with the caesium frequency standard . Though the Josephson effect is still used to realize a volt, the constant used has changed slightly. For the Josephson constant , K J = 2 e / h (where e

150-722: The British Association for the Advancement of Science had defined the volt, ohm, and farad. In 1881, the International Electrical Congress, now the International Electrotechnical Commission (IEC), approved the volt as the unit for electromotive force. They made the volt equal to 10 cgs units of voltage, the cgs system at the time being the customary system of units in science. They chose such

165-584: The European consortium between 1959 and 1961, which made them the most numerous class of mainline electric locomotive until the WAG-1. The WAM-1 served both passenger and freight trains for over 40 years. This class though was initially not a great success provided the basic design for the WAM-4 which a number of other locomotives is based on. However, with the advent of new 3-phase locomotives like WAP-5 and WAP-7,

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180-639: The aging fleet of WAM-1 locomotives were relegated to hauling freight and doing shunting duties. Now the WAM-1 locomotives have been fully withdrawn from service and all except one have been scrapped. The single surviving unit named 'Jagjivan Ram' has been preserved at NRM New Delhi. Volt One volt is defined as the electric potential between two points of a conducting wire when an electric current of one ampere dissipates one watt of power between those points. It can be expressed in terms of SI base units ( m , kg , s , and A ) as Equivalently, it

195-525: The 💕 For the enclosure housing electrical connections, see Junction box . An electrical junction is a point or area where (a) two or more conductors or (b) different semiconducting regions of differing electrical properties make physical contact. Electrical junctions types include thermoelectricity junctions, metal–semiconductor junctions and p–n junctions . Junctions are either rectifying or non-rectifying. Non-rectifying junctions comprise ohmic contacts , which are characterised by

210-415: The galvanic response advocated by Luigi Galvani , Alessandro Volta developed the so-called voltaic pile , a forerunner of the battery , which produced a steady electric current . Volta had determined that the most effective pair of dissimilar metals to produce electricity was zinc and silver . In 1861, Latimer Clark and Sir Charles Bright coined the name "volt" for the unit of resistance. By 1873,

225-427: Was defined in 1893 as 1 ⁄ 1.434 of the emf of a Clark cell . This definition was abandoned in 1908 in favor of a definition based on the international ohm and international ampere until the entire set of "reproducible units" was abandoned in 1948. A 2019 revision of the SI , including defining the value of the elementary charge , took effect on 20 May 2019. Electrical junction From Misplaced Pages,

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