Becquerel

The characteristics of the ammeters required depend on the types of systems being studied. The current densities may vary from one system to another, however the surfaces are what constitute the parameter which varies to the largest degree. The current scale must therefore be very wide. 

The following examples give various orders of magnitude. 

It is necessary to supply energy to the electrochemical system whenever it is working as an electric load (electrolyser mode). The most frequently used supply devices are electric current sources and voltage sources. A mere variable charge resistance can suffice to study an electrochemical system in the power supply mode. 

The setup uses a source of... controlled current controlled voltage 

Opting in favourof one of these two command modes is not always straightforward. 

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Inhalation, injection, or body exposure to radium can cause cancer and other body disorders. The maximum permissible border in the total body for 226Ra is 7400 becquerel. 

Bmnauer-Emmett-TeUer (adsorption equation) twice daily t-butyloxycarbonyl biochemical (biological) oxygen demand boiling point becquerel... 

Radioactive waste is characterized by volume and activity, defined as the number of disintegrations per second, known as becquerels. Each radionucHde has a unique half-life,, and corresponding decay constant, A = 0.693/tj 2 For a component radionucHde consisting of JS1 atoms, the activity, M, is defined as... 

In 1896, only a few months after Roentgen aimounced the observation of x-rays, Becquerel reported the additional observation of penetrating radiation emitted from certain natural materials, a phenomenon that Marie Curie would later name radioactivity. This phenomenon had a much less glamorous development. Over a three-year period, Becquerel pubHshed three articles, decided there was Htfle else to learn about it, and went on to the study... 

The uranium ores from which this new radiation was discovered were fluorescent, and x-ray tubes fluoresced thus, an early hypothesis was that the visible fluorescence and the new penetrating radiation were related and would occur together. Becquerel did a series of careful experiments showing that penetrating radiation also came from some materials that did not fluoresce. 

The more penetrating P-rays were easily studied. In 1899 their direction of deflection in a magnetic field was observed, indicating the negative charge. Then Becquerel was able to deflect P-rays in electric and magnetic fields and thereby deterrnined the charge-to-mass ratio. This ratio showed that the mass was much smaller than that of any atom and corresponded to that of electrons. 

The photovoltaic effect, where an internal elecromotive force is created, was discovered by Becquerel (106) in 1839 in an electrolyte with selenium but the effect in a metal—Se contact was first reported by Adams and Day (107) in 1876. The first practical photovoltaic cell was constmcted by Uljanin (108) in 1888. 

Ra.dia.tlon Units. Units in use for activity of a radionucHde, ie, the curie, the roentgen (exposure to x and gamma rays), the rad (absorbed dose), and the rem (dose equivalent), should eventually be replaced by the becquerel (Bq), coulomb per kilogram (C/kg), gray (Gy), and the sievert (Sv), respectively. 

In 1896, Becquerel discovered that uranium was radioactive (3). Becquerel was studying the duorescence behavior of potassium uranyl sulfate, and observed that a photographic plate had been darkened by exposure to the uranyl salt. Further investigation showed that all uranium minerals and metallic uranium behaved in this same manner, suggesting that this new radioactivity was a property of uranium itself In 1934, Fermi bombarded uranium with neutrons to produce new radioactive elements (4). 

The activity of a sample, source or contaminated material is the rate at which radioactive disintegrations are taking place. The initial term, named by Madam Curie for her husband was, the Curie (Table 8.3-1). The modem unit is the Becquerel named after the discoverer of... 

Curie (Ci) A unit of radioactivity, related to the emission from 1 g of radium, it is equal to 3.7 x 10 disintegrations per gram per second. This unit has been replaced by the Becquerel (Bq) 1... 

Ci (curie) = 3.7 x 10 °Bq (becquerel) 1 Bq = 1 s . ] Tritium is one of the least toxic of radioisotopes and shielding is unnecessary however, precautions must be taken against ingestion, and no work should be carried out without appropriate statutory authorization and adequate radiochemical facilities. 

Edmond Becquerel was one of a family of scientists. His father, Antoine-Cesar, was professor of physics at the Museum d Histoire Naturelle, and his son, [Antoine-] Henri Becquerel, also a physicist, discovered the phenomenon of radioactivity (for which he received the Nobel Prize in 1903). 

The discovery and detailed investigations of the phenomenon of fluorescence is generally considered the main contribution of Edmond Becquerel. It had the further impact of leading later to the discovery of radioactivity by his son Henri, as Henri continued th ese studies, including among the substances examined salts of uranium. 

Edmond Becquerel was interested in and dedicated to science in general. He was a very careful and imaginative experimenter with an acute sense of the practical aspects of science. He put great effort and insight into exploring the practical uses of physics, especially the new phenomena of electricity and magnetism or, when combined, electromagnetism. 

Becquerel, II. (1892). La chaire de physique du Museum. Revue Saenufique 49 674-678. 

Vinlle, J. (1892). L neuvre scientifique de M. Edmond Becquerel. Revue Scientifique 49 353-360. 

Curie chose for her dissertation research the new topic of uranium rays, a phenomenon that had only recently been observed by Henri Becqiierel. The mystery was the source of the energy that allowed uranium salts to expose even covered photographic plates. Curie s first efforts in the field were systematic examinations of numerous salts to determine which salts might emit rays similar to those of Becquerel s uranium. After discovering that both thorium and uranium were sources of this radiation. Curie proposed the term radioactive to replace uranium rays. She also discovered that the intensity of the emissions depended not on the chemical... 

The most important contribution I lertz made in this inaugural lecture was his prediction, based on his estimates of the energy sources available, that ultimately the Earth was completely dependent on the Sun for the light and heat it needed to support life. Of course, this picture would change after Henri Becquerel discovered radioactivity in 1896, and thus introduced the nuclear age of physics. 

The development of particle accelerators grew out of the discovery of radioactivity in uranium by Henri Becquerel in Paris in 1896. Some years later, due to the work of Ernest Rutherford and others, it was found that the radioactivity discovered by Becquerel was the emission o particles with kinetic energies o several MeV from uranium nuclei. Research using the emitted particles began shortly thereafter. It was soon realized that if scientists were to learn more about the properties of subatomic particles, they had to be accelerated to energies greater than those attained in natural radioactivity. 

In 1839 Alexandre-Edmtmd Becquerel, a French experimental physicist, did the earliest recorded experiments with the photovoltaic effect. Becquerel discovered the photovoltaic effect while experimenting with an electrolytic cell made up of two metal... 

Marie and Irene Curie, and their husbands, Pierre Curie and Frederic Joliot. Marie Curie (1867-1934) was born Maria Sklodowska in Warsaw, Poland, then a part of the Russian empire. In 1891 she emigrated to Paris to study at the Sorbonne, where she met and married a French physicist, Pierre Curie (1859-1906). The Curies were associates of Henri Becquerel, the man who discovered that uranium salts are radioactive. They showed that thorium, like uranium, is radioactive and that the amount of radiation emitted is directly proportional to the amount of uranium or thorium in the sample. 

In 1903, the Curies received the Nobel Prize in physics (with Becquerel) for the discovery of radioactivity. Three years later, Pierre Curie died at the age of 46, the victim of a tragic accident. Fie stepped from behind a carriage in a busy Paris street and was run down by a horse-driven truck. That same year, Marie became the first woman instructor at the Sorbonne. In 1911, she won the Nobel Prize in chemistry for the discovery of radium and polonium, thereby becoming the first person to win two Nobel Prizes. 

FIGURE 17.2 Henri Becquerel discovered radioactivity when he noticed that an unexposed photographic plate left near some uranium oxide became fogged. This photograph shows one of his original plates annotated with his record of the event. 

In 1896, the French scientist Fienri Becquerel happened to store a sample of uranium oxide in a drawer that contained some photographic plates (Fig. 17.2). He was astonished to find that the uranium compound darkened the plates even though they were covered with an opaque material. Becquerel realized that the uranium compound must give off some kind of radiation. Marie Sklodowska Curie (Fig. 17.3), a young Polish doctoral student, showed that the radiation, which she called radioactivity, was emitted by uranium regardless of the compound in which it was found. She concluded that the source must be the uranium atoms themselves. Together with her husband, Pierre, she went on to show that thorium, radium, and polonium are also radioactive. 

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