In physics, an electronvolt is the amount of kinetic energy gained by a single electron accelerating from rest through an electric potential difference of one volt in vacuum. When used as a unit of energy, the numerical value of 1 eV in joules is equivalent to the numerical value of the charge of an electron in coulombs. Under the 2019 redefinition of the SI base units, this sets 1 eV equal to 1.602176634×10−19 J. Historically, the electronvolt was devised as a standard unit of measure through its usefulness in electrostatic particle accelerator sciences, because a particle with electric charge q has an energy E = qV after passing through the potential V, it is a common unit of energy within physics used in solid state, atomic and particle physics. It is used with the metric prefixes milli-, kilo-, mega-, giga-, tera-, peta- or exa-. In some older documents, in the name Bevatron, the symbol BeV is used, which stands for billion electronvolts. An electronvolt is the amount of kinetic energy gained or lost by a single electron accelerating from rest through an electric potential difference of one volt in vacuum.
Hence, it has a value of one volt, 1 J/C, multiplied by the electron's elementary charge e, 1.602176634×10−19 C. Therefore, one electronvolt is equal to 1.602176634×10−19 J. The electronvolt, as opposed to the volt, is not an SI unit; the electronvolt is a unit of energy. The SI unit for energy is the joule. By mass–energy equivalence, the electronvolt is a unit of mass, it is common in particle physics, where units of mass and energy are interchanged, to express mass in units of eV/c2, where c is the speed of light in vacuum. It is common to express mass in terms of "eV" as a unit of mass using a system of natural units with c set to 1; the mass equivalent of 1 eV/c2 is 1 eV / c 2 = ⋅ 1 V 2 = 1.782 661 92 × 10 − 36 kg. For example, an electron and a positron, each with a mass of 0.511 MeV/c2, can annihilate to yield 1.022 MeV of energy. The proton has a mass of 0.938 GeV/c2. In general, the masses of all hadrons are of the order of 1 GeV/c2, which makes the GeV a convenient unit of mass for particle physics: 1 GeV/c2 = 1.78266192×10−27 kg.
The unified atomic mass unit exactly 1 gram divided by the Avogadro number, is the mass of a hydrogen atom, the mass of the proton. To convert to electron volts, use the formula: 1 u = 931.4941 MeV/c2 = 0.9314941 GeV/c2. In high-energy physics, the electronvolt is used as a unit of momentum. A potential difference of 1 volt causes an electron to gain an amount of energy; this gives rise to usage of eV as units of momentum, for the energy supplied results in acceleration of the particle. The dimensions of momentum units are LMT−1; the dimensions of energy units are L2MT−2. Dividing the units of energy by a fundamental constant that has units of velocity, facilitates the required conversion of using energy units to describe momentum. In the field of high-energy particle physics, the fundamental velocity unit is the speed of light in vacuum c. By dividing energy in eV by the speed of light, one can describe the momentum of an electron in units of eV/c; the fundamental velocity constant c is dropped from the units of momentum by way of defining units of length such that the value of c is unity.
For example, if the momentum p of an electron is said to be 1 GeV the conversion to MKS can be achieved by: p = 1 GeV / c = ⋅ ⋅ = 5.344 286 × 10 − 19 kg ⋅ m / s. In particle physics, a system of "natural units" in which the speed of light in vacuum c and the reduced Planck constant ħ are dimensionles
Kado Station is a railway station in the town of Mitane, Yamamoto District Akita Prefecture, operated by East Japan Railway Company. Kado Station is served by the Ōu Main Line, is located 338.4 km from the terminus of the line at Fukushima Station. Kado Station has one side platform and one island platform serving three tracks, connected by a footbridge. Track 2 is used for freight trains changing direction. Kado Station is a simple consignment station, administered by Higashi-Noshiro Station, operated by Mitane municipal authority, with point-of-sales terminal installed. Ordinary tickets, express tickets, reserved-seat tickets for all JR lines are on sale. Kado Station was opened on August 1, 1902 as a station on the Japanese Government Railways, serving the town of Kado, Akita; the JGR became the JNR after World War II. The station was absorbed into the JR East network upon the privatization of the JNR on April 1, 1987. A new station building was completed in July 2007. In fiscal 2018, the station was used by an average of 135 passengers daily.
The Mier expedition was an unsuccessful military operation launched in November 1842 by a Texian militia against Mexican border settlements. It included a major battle at Ciudad Mier on December 27, 1842, which the Mexicans won; the Texian attack was launched in hopes of financial gain and in retaliation for the Dawson Massacre earlier that year, in which thirty-six Texas militia were killed by the Mexican Army. Both conflicts were part of continuing efforts by each side to control the land between the Rio Grande and Nueces River; the Republic of Texas believed that this territory had been ceded to it in the Treaties of Velasco, by which they gained independence. Antonio López de Santa Anna, the ruler of Mexico, was defeated by Texians at the Battle of San Jacinto and signed the Treaties of Velasco in 1836, ceding Texas territory from Mexican control. But, his forces continued to invade the Republic of Texas with the goal of regaining control of the territory between the Rio Grande and Nueces River.
Texas had hardly any settlements there. On September 17, 1842, Texian and Mexican forces engaged at Salado Creek, east of San Antonio. After a separate favorable Texian engagement earlier in the day, a reinforcement company of 54 Texas militia from Fayette County, under the command of Nicholas Mosby Dawson, began advancing on the rear of the Mexican Army; the Mexican commander, General Adrián Woll, sent 500 of his cavalrymen and two cannons to attack the group. The Texians held their own against the Mexican soldiers, but their fatalities mounted after the cannons came within range; the battle lasted just over an hour, resulting in 36 Texians dead and 15 captured in what Texans called the Dawson Massacre. On November 25, 1842, Alexander Somervell, a Texan customs officer from Matagorda Island, left San Antonio with 700 men under his command on a military expedition to punish the Mexican Army for raids in Texas; the Somervell Expedition recaptured Laredo on December 7, 1842, with a reduced force of 500, took the Mexican town of Guerrero.
Lacking serious backing for the expedition from the Republic of Texas, Somervell ordered his men to disband and return home on December 19, 1842. Five captains and their men disobeyed. More men were gathered at La Grange, they continued the march to Ciudad Mier under the command of William S. Fisher. On December 20, 1842, some 308 Texan soldiers, who had ignored orders to pull back from the Rio Grande to Gonzales, approached Ciudad Mier, they camped on the Texas side of the Rio Grande. 700 soldiers participated in the capture of the town, while the others remained behind as the camp guard. The Texans were unaware that 3,000 Mexican troops were in the area under the command of generals Francisco Mexia and Pedro de Ampudia. In the Battle of Mier that resulted, the Texians were outnumbered ten to one, they inflicted heavy casualties on the Mexicans—650 dead and 200 wounded—but they were forced to surrender on December 26. The Mexicans took 243 Texans as prisoner and marched them toward Mexico City via Matamoros and Monterrey, Nuevo León.
On February 11, 1843, 181 Texans escaped but, by the end of the month, the lack of food and water in the mountainous Mexican desert resulted in 176 of them surrendering or being recaptured. This was in the vicinity of Tamaulipas; when the prisoners reached Saltillo, they learned that an outraged Santa Anna had ordered all the escapees to be executed, but General and Governor Francisco Mexía of the state of Coahuila refused to follow the order. The new commander, Colonel Domingo Huerta, moved the prisoners to El Rancho Salado. By this time, diplomatic efforts on behalf of Texas by the foreign ministers of the United States and Great Britain led Santa Anna to compromise: he said one in ten of the prisoners would be killed. To help determine who would die, Huerta had 17 black beans placed in a pot. In what came to be known as the Black Bean Episode or the Bean Lottery, the Texans were blindfolded and ordered to draw beans. Officers and enlisted men, in alphabetical order, were ordered to draw; the seventeen men who drew black beans were allowed to write letters home before being executed by firing squad.
On the evening of March 25, 1843, the Texians were shot in two groups, one of nine men and one of eight. According to legend, Huerta placed the black beans in the jar last and had the officers pick first, so that they would make up the majority of those killed; the first Texan to draw a black bean was Major James Decatur Cocke. A witness recalled that Cocke held up the bean between his forefinger and thumb, with a smile of contempt, said, "Boys, I told you so, he told a fellow Texan, "They only rob me of forty years." Fearing that the Mexicans would strip his body after he was dead, he removed his pants and gave them to a companion whose clothing was in worse shape. He was shot with the sixteen others who drew black beans on March 25, 1843, his last words were reported to have been, "Tell my friends I die with grace." The other sixteen who drew black beans in the lottery were William Mosby Eastland, Patrick Mahan, James M. Ogden, James N. Torrey, Martin Carroll Wing, John L. Cash, Robert Holmes Dunham, Edward E. Este, Robert Harris, Thomas L. Jones, Christopher Roberts, William N. Rowan, James L. Shepherd, J. N. M. Thomson, James Turnbull, Henry Walling.
Shepherd survived the firing squad by pretending to be dead. The guards left him for dead in the courtyard, he escaped in the night but was recaptured and shot. Eastland County, Texas, is named after William Mosby East