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Lycopodium Powder
Lycopodium powder is a yellow-tan dust-like powder, consisting of the dry spores of clubmoss plants, or various fern relatives. When it is mixed with air, the spores are highly flammable and are used to create dust explosions as theatrical special effects. The powder was traditionally used in physics experiments to demonstrate phenomena such as Brownian motion. Composition The powder consists of the dry spores of clubmoss plants, or various fern relatives principally in the genera '' Lycopodium'' and '' Diphasiastrum''. The preferred source species are ''Lycopodium clavatum'' (stag's horn clubmoss) and ''Diphasiastrum digitatum'' (common groundcedar), because these widespread and often locally abundant species are both prolific in their spore production and easy to collect. Main uses Today, the principal use of the powder is to create flashes or flames that are large and impressive but relatively easy to manage safely in magic acts and for cinema and theatrical special ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Micrometre
The micrometre (English in the Commonwealth of Nations, Commonwealth English as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American English), also commonly known by the non-SI term micron, is a unit of length in the International System of Units (SI) equalling (SI standard prefix "micro-" = ); that is, one millionth of a metre (or one thousandth of a millimetre, , or about ). The nearest smaller common SI Unit, SI unit is the nanometre, equivalent to one thousandth of a micrometre, one millionth of a millimetre or one billionth of a metre (). The micrometre is a common unit of measurement for wavelengths of infrared radiation as well as sizes of biological cell (biology), cells and bacteria, and for grading wool by the diameter of the fibres. The width of a single human hair ranges from approximately 20 to . Examples Between 1 μm and 10 μm: * 1–10 μm – length of a typical bacterium * 3–8 μm – width of str ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrostatic Charge
Electric charge (symbol ''q'', sometimes ''Q'') is a physical property of matter that causes it to experience a force when placed in an electromagnetic field. Electric charge can be ''positive'' or ''negative''. Like charges repel each other and unlike charges attract each other. An object with no net charge is referred to as electrically neutral. Early knowledge of how charged substances interact is now called classical electrodynamics, and is still accurate for problems that do not require consideration of quantum effects. In an isolated system, the total charge stays the same - the amount of positive charge minus the amount of negative charge does not change over time. Electric charge is carried by subatomic particles. In ordinary matter, negative charge is carried by electrons, and positive charge is carried by the protons in the nuclei of atoms. If there are more electrons than protons in a piece of matter, it will have a negative charge, if there are fewer it will have a p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sound Wave
In physics, sound is a vibration that propagates as an acoustic wave through a transmission medium such as a gas, liquid or solid. In human physiology and psychology, sound is the ''reception'' of such waves and their ''perception'' by the brain. Only acoustic waves that have frequencies lying between about 20 Hz and 20 kHz, the audio frequency range, elicit an auditory percept in humans. In air at atmospheric pressure, these represent sound waves with wavelengths of to . Sound waves above 20 kHz are known as ultrasound and are not audible to humans. Sound waves below 20 Hz are known as infrasound. Different animal species have varying hearing ranges, allowing some to even hear ultrasounds. Definition Sound is defined as "(a) Oscillation in pressure, stress, particle displacement, particle velocity, etc., propagated in a medium with internal forces (e.g., elastic or viscous), or the superposition of such propagated oscillation. (b) Auditory sens ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Physics
Physics is the scientific study of matter, its Elementary particle, fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which relates to the order of nature, or, in other words, to the regular succession of events." It is one of the most fundamental scientific disciplines. "Physics is one of the most fundamental of the sciences. Scientists of all disciplines use the ideas of physics, including chemists who study the structure of molecules, paleontologists who try to reconstruct how dinosaurs walked, and climatologists who study how human activities affect the atmosphere and oceans. Physics is also the foundation of all engineering and technology. No engineer could design a flat-screen TV, an interplanetary spacecraft, or even a better mousetrap without first understanding the basic laws of physics. (...) You will come to see physics as a towering achievement of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Natural History Museum, London
The Natural History Museum in London is a museum that exhibits a vast range of specimens from various segments of natural history. It is one of three major museums on Exhibition Road in South Kensington, the others being the Science Museum (London), Science Museum and the Victoria and Albert Museum. The Natural History Museum's main frontage, however, is on Cromwell Road. The museum is home to life and earth science specimens comprising some 80 million items within five main collections: botany, entomology, mineralogy, palaeontology and zoology. The museum is a centre of research specialising in Taxonomy (biology), taxonomy, identification and conservation. Given the age of the institution, many of the collections have great historical as well as scientific value, such as specimens collected by Charles Darwin. The museum is particularly famous for its exhibition of dinosaur skeletons and ornate architecture—sometimes dubbed a ''cathedral of nature''—both exemplified by the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Medical Gloves
Medical gloves are disposable gloves used during medical examinations and procedures to help prevent cross-contamination between caregivers and patients. Medical gloves are made of different polymers including latex, nitrile rubber, polyvinyl chloride and neoprene; they come unpowdered, or powdered with corn starch to lubricate the gloves, making them easier to put on the hands. Corn starch replaced tissue-irritating lycopodium powder and talc, but even corn starch can impede healing if it gets into tissues (as during surgery). As such, unpowdered gloves are used more often during surgery and other sensitive procedures. Special manufacturing processes are used to compensate for the lack of powder. There are two main types of medical gloves: examination and surgical. Surgical gloves have more precise sizing with a better precision and sensitivity and are made to a higher standard. Examination gloves are available either sterile or non-sterile, while surgical gloves are generall ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Condom
A condom is a sheath-shaped Barrier contraception, barrier device used during sexual intercourse to reduce the probability of pregnancy or a Sexually transmitted disease, sexually transmitted infection (STI). There are both external condoms, also called male condoms, and Internal condom, internal (female) condoms. The external condom is rolled onto an erect penis before intercourse and works by forming a physical barrier which limits skin-to-skin contact, exposure to Bodily Fluids, fluids, and blocks semen from entering the body of a sexual partner. External condoms are typically made from latex and, less commonly, from polyurethane, polyisoprene, or lamb intestine. External condoms have the advantages of ease of use, ease of access, and few side effects. Individuals with latex allergy should use condoms made from a material other than latex, such as polyurethane. Internal condoms are typically made from polyurethane and may be used multiple times. With proper use—and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Natural Rubber
Rubber, also called India rubber, latex, Amazonian rubber, ''caucho'', or ''caoutchouc'', as initially produced, consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds. Types of polyisoprene that are used as natural rubbers are classified as elastomers. Currently, rubber is harvested mainly in the form of the latex from the Hevea brasiliensis, Pará rubber tree (''Hevea brasiliensis'') or others. The latex is a sticky, milky and white colloid drawn off by making incisions in the bark and collecting the fluid in vessels in a process called "tapping". Manufacturers refine this latex into the rubber that is ready for commercial processing. Natural rubber is used extensively in many applications and products, either alone or in combination with other materials. In most of its useful forms, it has a large stretch ratio and high resilience and also is buoyant and water-proof. Industrial demand for rubber-like materials began to out ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lubricating
Lubrication is the process or technique of using a lubricant to reduce friction and wear and tear in a contact between two surfaces. The study of lubrication is a discipline in the field of tribology. Lubrication mechanisms such as fluid-lubricated systems are designed so that the applied load is partially or completely carried by hydrodynamic or hydrostatic pressure, which reduces solid body interactions (and consequently friction and wear). Depending on the degree of surface separation, different lubrication regimes can be distinguished. Adequate lubrication allows smooth, continuous operation of machine elements, reduces the rate of wear, and prevents excessive stresses or seizures at bearings. By repelling water and other substances, it also reduces corrosion. When lubrication breaks down, components can rub destructively against each other, causing heat, local welding, destructive damage and failure. Lubrication mechanisms Fluid-lubricated systems As the load increases ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ice Cream
Ice cream is a frozen dessert typically made from milk or cream that has been flavoured with a sweetener, either sugar or an alternative, and a spice, such as Chocolate, cocoa or vanilla, or with fruit, such as strawberries or peaches. Food colouring is sometimes added in addition to Food stabilizer, stabilizers. The mixture is cooled below the freezing point of water and stirred to incorporate air spaces and prevent detectable ice crystals from forming. It can also be made by Whisk, whisking a flavoured cream base and liquid nitrogen together. The result is a smooth, semi-solid foam that is solid at very low temperatures (below ). It becomes more Ductility, malleable as its temperature increases. Ice cream may be served in dishes, eaten with a spoon, or licked from edible wafer Ice cream cone, ice cream cones held by the hands as finger food. Ice cream may be served with other desserts—such as cake or pie—or used as an ingredient in cold dishes—like ice cream floats, s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pill (pharmacy)
A tablet (also known as a pill) is a Pharmacy, pharmaceutical oral dosage form (''oral solid dosage'', or OSD) or solid unit dosage form. Tablets may be defined as the solid unit dosage form of medication with suitable excipients. It comprises a mixture of active substances and excipients, usually in powder (substance), powder form, that are pressed or compacted into a solid dose. The main advantages of tablets are that they ensure a consistent dose of medicine that is easy to consume. Tablets are prepared either by moulding or by Compression (physics), compression. The excipients can include diluents, Binder (material), binders or granulating agents, glidants (flow aids) and lubricants to ensure efficient tabletting; Excipient#Disintegrants, disintegrants to promote tablet break-up in the digestive tract; sweeteners or flavours to enhance taste; and pigments to make the tablets visually attractive or aid in visual identification of an unknown tablet. A polymer coating is often ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
