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Lippmann Electrometer
A Lippmann electrometer is a device for detecting small rushes of electric current and was invented by Gabriel Lippmann in 1873.Fritz Scholz''Electroanalytical Methods: Guide to Experiments and Applications'' 2nd ed., Springer, 2010. The device consists of a tube which is thick on one end and very thin on the other. The thin end is designed to act as a capillary tube. The tube is half-filled with mercury with a small amount of dilute sulfuric acid above the mercury in the capillary tube. Metal wires are connected at the thick end into the mercury and at the thin end into the sulfuric acid. When the pulse of electricity arrives it changes the surface tension of the mercury and allows it to leap up a short distance in the capillary tube. This device was used in the first practical ECG Electrocardiography is the process of producing an electrocardiogram (ECG or EKG), a recording of the heart's electrical activity. It is an electrogram of the heart which is a graph of voltage v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electric Current
An electric current is a stream of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is measured as the net rate of flow of electric charge through a surface or into a control volume. The moving particles are called charge carriers, which may be one of several types of particles, depending on the conductor. In electric circuits the charge carriers are often electrons moving through a wire. In semiconductors they can be electrons or holes. In an electrolyte the charge carriers are ions, while in plasma, an ionized gas, they are ions and electrons. The SI unit of electric current is the ampere, or ''amp'', which is the flow of electric charge across a surface at the rate of one coulomb per second. The ampere (symbol: A) is an SI base unit. Electric current is measured using a device called an ammeter. Electric currents create magnetic fields, which are used in motors, generators, inductors, and transformers. In ordinary con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gabriel Lippmann
Jonas Ferdinand Gabriel Lippmann (16 August 1845 – 13 July 1921) was a Franco-Luxembourgish physicist and inventor, and Nobel laureate in physics for his method of reproducing colours photographically based on the phenomenon of interference. His parents were French Jews. Early life and education Gabriel Lippmann was born in Bonnevoie, Luxembourg (Luxembourgish: Bouneweg), on 16 August 1845. At the time, Bonnevoie was part of the commune of Hollerich (Luxembourgish: Hollerech) which is often given as his place of birth. (Both places, Bonnevoie and Hollerich, are now districts of Luxembourg City.) His father, Isaïe, a French Jew born in Ennery near Metz, managed the family glove-making business at the former convent in Bonnevoie. In 1848, the family moved to Paris where Lippmann was initially tutored by his mother, Miriam Rose (Lévy), before attending the Lycée Napoléon (now Lycée Henri-IV). He was said to have been a rather inattentive but thoughtful pupil with a special ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Capillary Action
Capillary action (sometimes called capillarity, capillary motion, capillary rise, capillary effect, or wicking) is the process of a liquid flowing in a narrow space without the assistance of, or even in opposition to, any external forces like gravity. The effect can be seen in the drawing up of liquids between the hairs of a paint-brush, in a thin tube, in porous materials such as paper and plaster, in some non-porous materials such as sand and liquefied carbon fiber, or in a biological cell. It occurs because of intermolecular forces between the liquid and surrounding solid surfaces. If the diameter of the tube is sufficiently small, then the combination of surface tension (which is caused by cohesion within the liquid) and adhesive forces between the liquid and container wall act to propel the liquid. Etymology Capillary comes from the Latin word capillaris, meaning "of or resembling hair." The meaning stems from the tiny, hairlike diameter of a capillary. While capilla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mercury (element)
Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver and was formerly named hydrargyrum ( ) from the Greek words, ''hydor'' (water) and ''argyros'' (silver). A heavy, silvery d-block A block of the periodic table is a set of elements unified by the atomic orbitals their valence electrons or vacancies lie in. The term appears to have been first used by Charles Janet. Each block is named after its characteristic orbital: s-blo ... element, mercury is the only metallic element that is known to be liquid at standard temperature and pressure; the only other element that is liquid under these conditions is the halogen bromine, though metals such as caesium, gallium, and rubidium melt just above room temperature. Mercury occurs in deposits throughout the world mostly as cinnabar (mercuric sulfide). The red pigment vermilion is obtained by Mill (grinding), grinding natural cinnabar or synthetic mercuric sulfide. Mercury is used in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sulfuric Acid
Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid ( Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen and hydrogen, with the molecular formula . It is a colorless, odorless and viscous liquid that is miscible with water. Pure sulfuric acid does not exist naturally on Earth due to its strong affinity to water vapor; it is hygroscopic and readily absorbs water vapor from the air. Concentrated sulfuric acid is highly corrosive towards other materials, from rocks to metals, since it is an oxidant with powerful dehydrating properties. Phosphorus pentoxide is a notable exception in that it is not dehydrated by sulfuric acid, but to the contrary dehydrates sulfuric acid to sulfur trioxide. Upon addition of sulfuric acid to water, a considerable amount of heat is released; thus the reverse procedure of adding water to the acid should not be performed since the heat released may boi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Surface Tension
Surface tension is the tendency of liquid surfaces at rest to shrink into the minimum surface area possible. Surface tension is what allows objects with a higher density than water such as razor blades and insects (e.g. water striders) to float on a water surface without becoming even partly submerged. At liquid–air interfaces, surface tension results from the greater attraction of liquid molecules to each other (due to cohesion) than to the molecules in the air (due to adhesion). There are two primary mechanisms in play. One is an inward force on the surface molecules causing the liquid to contract. Second is a tangential force parallel to the surface of the liquid. This ''tangential'' force is generally referred to as the surface tension. The net effect is the liquid behaves as if its surface were covered with a stretched elastic membrane. But this analogy must not be taken too far as the tension in an elastic membrane is dependent on the amount of deformation of the m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Augustus Desiré Waller
Augustus Desiré Waller FRS (12 July 1856 – 11 March 1922) was a British physiologist and the son of Augustus Volney Waller. He was born in Paris, France. He studied medicine at Aberdeen University, where he qualified in 1878 and obtained his M.D. in 1881. In 1883, he became a lecturer in physiology at the London School of Medicine for Women. Whilst there he met his wife, Alice Palmer, who was one of his students and daughter of George Palmer, MP for Reading and founder of the biscuit manufacturers Huntley and Palmer. In 1884 he became a lecturer in physiology at St Mary's Hospital. In 1887 he used a capillary electrometer to record the first human electrocardiogram. He created the first practical ECG machine with surface electrodes. He lectured on it in Europe and America, often using his dog Jimmy in his ECG demonstrations. Initially Waller did not think electrocardiograms would be useful in hospitals. However, eventually other physiologists such as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrocapillarity
Electrocapillarity or electrocapillary phenomena are the phenomena related to changes in the surface energy (or interfacial tension) of the dropping mercury electrode (DME), or in principle, any electrode, as the electrode potential changes or the electrolytic solution composition and concentration change. The term "electro-capillary" is used to describe the change in mercury (Hg) electrode potential as a function of the change in the surface or interfacial tension of the Hg determined by the capillary rise method. The phenomena are the historic main contributions for understanding and validating the models of the structure of the electrical double layer. The phenomena are related to the electrokinetic phenomena and consequently to the colloid chemistry. Interfacial tension The interfacial (surface) tension, St, (dyne cm−1), can be calculated by applying the equation of capillary rise method (when the contact angle Ө → 0): St = \frac where: * h (cm) is the height of Hg co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrophysiology
Electrophysiology (from Greek , ''ēlektron'', "amber" etymology of "electron"">Electron#Etymology">etymology of "electron" , ''physis'', "nature, origin"; and , '' -logia'') is the branch of physiology that studies the electrical properties of biological cells and tissues. It involves measurements of voltage changes or electric current or manipulations on a wide variety of scales from single ion channel proteins to whole organs like the heart. In neuroscience, it includes measurements of the electrical activity of neurons, and, in particular, action potential activity. Recordings of large-scale electric signals from the nervous system, such as electroencephalography, may also be referred to as electrophysiological recordings. They are useful for electrodiagnosis and monitoring. Definition and scope Classical electrophysiological techniques Principle and mechanisms Electrophysiology is the branch of physiology that pertains broadly to the flow of ions (ion current) in biologi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
