The northern pike, known as a pike in Britain, most of Canada, most parts of the United States, is a species of carnivorous fish of the genus Esox. They are typical of fresh waters of the Northern Hemisphere. Pike can grow to a large size: the average length is about 40–55 cm, with maximum recorded lengths of up to 150 cm and published weights of 28.4 kg. The IGFA recognizes a 25 kg pike caught by Lothar Louis in Lake on Grefeern, Germany, on 16 October 1986, as the all-tackle world-record northern pike; the northern pike gets its common name from its resemblance to the pole-weapon known as the pike. Various other unofficial trivial names are common pike, great northern pike, Lakes pike, snot rocket, slough shark, slimer, slough snake, gator, jackfish, hammer handle, other such names as long head and pointy nose. Numerous other names can be found in Field Museum Zool. Leaflet Number 9, its earlier common name, the luci, is used in heraldry. Northern pike are most olive green, shading from yellow to white along the belly.
The flank is marked with a few to many dark spots on the fins. Sometimes, the fins are reddish. Younger pike have yellow stripes along a green body; the lower half of the gill cover lacks scales, it has large sensory pores on its head and on the underside of its lower jaw which are part of the lateral line system. Unlike the similar-looking and related muskellunge, the northern pike has light markings on a dark body background and fewer than six sensory pores on the underside of each side of the lower jaw. A hybrid between northern pike and muskellunge is known as a tiger muskellunge. In the hybrids, the males are invariably sterile, while females are fertile, may back-cross with the parent species. Another form of northern pike, the silver pike, is not a subspecies but rather a mutation that occurs in scattered populations. Silver pike, sometimes called silver muskellunge, lack the rows of spots and appear silver, white, or silvery-blue in color; when ill, silver pike have been known to display a somewhat purplish hue.
In Italy, the newly identified species Esox cisalpinus was long thought to be a color variation of the northern pike, but was in 2011 announced to be a species of its own. Northern pike in North America reach the size of their European counterparts, it was caught in Great Sacandaga Lake on 15 September 1940 by Peter Dubuc. Reports of far larger pike have been made, but these are either misidentifications of the pike's larger relative, the muskellunge, or have not been properly documented and belong in the realm of legend; as northern pike grow longer, they increase in weight, the relationship between length and weight is not linear. The relationship between total length and total weight for nearly all species of fish can be expressed by an equation of the form W = c L b. Invariably, b is close to 3.0 for all species, c is a constant that varies among species. For northern pike, b = 3.096 and c = 0.000180. The relationship described in this section suggests a 20-inch northern pike will weigh about 2 lb, while a 26-inch northern pike will weigh about 4 lb.
Pike are found in sluggish streams and shallow, weedy places in lakes and reservoirs, as well as in cold, rocky waters. They are typical ambush predators, they inhabit any water body that contains fish, but suitable places for spawning are essential. Because of their cannibalistic nature, young pike need places where they can take shelter between plants so they are not eaten. In both cases, rich submerged vegetation is needed. Pike are found in brackish water, except for the Baltic Sea area, here they can be found spending time both in the mouths of rivers and in the open brackish waters of the Baltic Sea, it is normal for pike to return to fresh water after a period in these brackish waters. They seem to prefer water with less turbidity, but, related to their dependence on the presence of vegetation and not to their being sight hunters; the northern pike is a aggressive species with regard to feeding. For example, when food sources are scarce, cannibalism develops, starting around five weeks in a small percentage of populations.
This cannibalism occurs. One can expect this because when food is scarce, Northern pike fight for survival, such as turning on smaller pike to feed. Pike tend to feed on smaller fish, such as the banded killifish. However, when pike exceed 700 mm long, they feed on larger fish; because of cannibalism when food is short, pike suffer a high young morta
In fishing, a gaff is a pole with a sharp hook on the end, used to stab a large fish and lift the fish into the boat or onto shore. Ideally, the hook is placed under the backbone. Gaffs are used when the weight of the fish exceeds the breaking point of the fishing line or the fishing pole. A gaff cannot be used if it is intended to release the fish unharmed after capture, unless the fish is skilfully gaffed in the lip, jaw, or lower gill using a thin gaff hook. A "flying gaff" is a specialized type of gaff used for securing and controlling large fish; the hook part of the gaff detaches. The head is secured to the boat with a length of heavy rope or cable
Copper has been used in electrical wiring since the invention of the electromagnet and the telegraph in the 1820s. The invention of the telephone in 1876 created further demand for copper wire as an electrical conductor. Copper is the electrical conductor in many categories of electrical wiring. Copper wire is used in power generation, power transmission, power distribution, telecommunications, electronics circuitry, countless types of electrical equipment. Copper and its alloys are used to make electrical contacts. Electrical wiring in buildings is the most important market for the copper industry. Half of all copper mined is used to manufacture electrical wire and cable conductors. Electrical conductivity is a measure of; this is an essential property in electrical wiring systems. Copper has the highest electrical conductivity rating of all non-precious metals: the electrical resistivity of copper = 16.78 nΩ•m at 20 °C. Specially-pure Oxygen-Free Electronic copper is about 1% more conductive; the theory of metals in their solid state helps to explain the unusually high electrical conductivity of copper.
In a copper atom, the outermost 4s energy zone, or conduction band, is only half filled, so many electrons are able to carry electric current. When an electric field is applied to a copper wire, the conduction of electrons accelerates towards the electropositive end, thereby creating a current; these electrons encounter resistance to their passage by colliding with impurity atoms, lattice ions, imperfections. The average distance travelled between collisions, defined as the "mean free path", is inversely proportional to the resistivity of the metal. What is unique about copper is its long mean free path; this mean free path increases as copper is chilled. Because of its superior conductivity, annealed copper became the international standard to which all other electrical conductors are compared. In 1913, the International Electrotechnical Commission defined the conductivity of commercially pure copper in its International Annealed Copper Standard, as 100% IACS = 58.0 MS/m at 20 °C, decreasing by 0.393%/°C.
Because commercial purity has improved over the last century, copper conductors used in building wire slightly exceed the 100% IACS standard. The main grade of copper used for electrical applications is electrolytic-tough pitch copper; this copper is at least 99.90% pure and has an electrical conductivity of at least 101% IACS. ETP copper contains a small percentage of oxygen. If high conductivity copper needs to be welded or brazed or used in a reducing atmosphere oxygen-free copper may be used. Several electrically conductive metals are less dense than copper, but require larger cross sections to carry the same current and may not be usable when limited space is a major requirement. Aluminium has 61% of the conductivity of copper; the cross sectional area of an aluminium conductor must be 56% larger than copper for the same current carrying capability. The need to increase the thickness of aluminium wire restricts its use in several applications, such as in small motors and automobiles. In some applications such as aerial electric power transmission cables, copper is used.
Silver, a precious metal, is the only metal with a higher electrical conductivity than copper. The electrical conductivity of silver is 106% of that of annealed copper on the IACS scale, the electrical resistivity of silver = 15.9 nΩ•m at 20 °C. The high cost of silver combined with its low tensile strength limits its use to special applications, such as joint plating and sliding contact surfaces, plating for the conductors in high-quality coaxial cables used at frequencies above 30 MHz Tensile strength measures the force required to pull an object such as rope, wire, or a structural beam to the point where it breaks; the tensile strength of a material is the maximum amount of tensile stress it can take before breaking. Copper’s higher tensile strength compared to aluminium is another reason why copper is used extensively in the building industry. Copper’s high strength resists stretching, neck-down, creep and breaks, thereby prevents failures and service interruptions. Copper is much heavier than aluminum for conductors of equal current carrying capacity, so the high tensile strength is offset by its increased weight.
Ductility is a material's ability to deform under tensile stress. This is characterized by the material's ability to be stretched into a wire. Ductility is important in metalworking because materials that crack or break under stress cannot be hammered, rolled, or drawn. Copper has a higher ductility than alternate metal conductors with the exception of silver; because of copper’s high ductility, it is easy to draw down to diameters with close tolerances. The stronger a metal is, the less pliable it is; this is not the case with copper. A unique combination of high strength and high ductility makes copper ideal for wiring systems. At junction boxes and at terminations, for example, copper can be bent and pulled without stretching or breaking. Creep is the gradual deformation of a material from constant expansions and contractions under “load, no-load” conditions; this process has adverse effects on electrical systems: terminations can become loose, causing connections to heat up or create dangerous arcing.
Copper has excellent creep characteristics. For other met
Fly fishing is an angling method in which an artificial "fly" is used to catch fish. The fly is cast using a fly rod and specialized weighted line. Casting a nearly weightless fly or "lure" requires casting techniques different from other forms of casting. Fly fishermen use hand tied flies that resemble natural invertebrates, other food organisms, or "lures" to provoke the fish to strike. Fly fishing can be done in salt water. North Americans distinguish freshwater fishing between cold-water species and warm-water species, notably bass. In Britain, where natural water temperatures vary less, the distinction is between game fishing for trout and salmon versus coarse fishing for other species. Techniques for fly fishing differ with habitat Author Izaak Walton called fly fishing "The Contemplative Man's Recreation". In fly fishing, fish are caught by using artificial flies that are cast with a fly rod and a fly line; the fly line is heavy enough to send the fly to the target. The main difference between fly fishing and spin or bait fishing is that in fly fishing the weight of the line carries the hook through the air, whereas in spin and bait fishing the weight of the lure or sinker at the end of the monofilament or braided line gives casting distance.
Artificial flies are of several types. Flies can be made either to float or sink, range in size from a few millimeters to 30 cm long. Artificial flies are made by fastening hair, feathers, or other materials, both natural and synthetic, onto a hook; the first flies were tied with natural materials, but synthetic materials are now popular and prevalent. Flies are tied in sizes and patterns to match local terrestrial and aquatic insects, baitfish, or other prey attractive to the target fish species. Fly fishing is most renowned as a method for catching trout and salmon, but it is used for a wide variety of species including pike, bass and carp, as well as marine species, such as redfish, tarpon and striped bass. Many fly anglers catch unintended species such as chub and rudd while fishing for'main target' species such as trout. A growing population of anglers attempt to catch as many different species as possible with the fly. With the advancement of technology and development of stronger rods and reels, larger predatory saltwater species such as wahoo, tuna and sharks have become target species on fly.
Realistically any fish can be targeted and captured on fly as long as the main food source is replicated by the fly itself and suitable gear is used. Many credit the first recorded use of an artificial fly to the Roman Claudius Aelianus near the end of the 2nd century, he described the practice of Macedonian anglers on the Astraeus River:...they have planned a snare for the fish, get the better of them by their fisherman's craft.... They fasten red wool... round a hook, fit on to the wool two feathers which grow under a cock's wattles, which in color are like wax. Their rod is six feet long, their line is the same length, they throw their snare, the fish and maddened by the color, comes straight at it, thinking from the pretty sight to gain a dainty mouthful. In his book Fishing from the Earliest Times, William Radcliff gave the credit to Martial, born some two hundred years before Aelianus, who wrote:... Who has not seen the scarus rise and killed by fraudful flies... The last word, somewhat indistinct in the original, is either "mosco" or "musca" but catching fish with fraudulent moss seems unlikely.
The traditional Japanese method of fly-fishing is known as "Tenkara". Tenkara originated in the mountains of Japan as a way for professional fishermen and inn-keepers to harvest the local fish, Ayu and char for selling and providing a meal to their guests. A small-stream fishing method, preferred for being efficient, where the long rod allowed the fisherman to place the fly where the fish would be. Another style of fishing in Japan is Ayu fishing; as written by historian Andrew Herd, in the book "The Fly", "Fly fishing became popular with Japanese peasants from the twelfth century onward...fishing was promoted to a pastime worthy of Bushi, as part of an official policy to train the Bushi's mind during peacetime." This refers to Ayu fishing, which uses a fly as lure, uses longer rods, but there is no casting technique required, it's more similar to dapping. Ayu was practiced in the lowlands. Fishing flies are thought to have originated in Japan for Ayu fishing over 430 years ago; these flies were made with needles that were bent into shape and used as fishing hooks dressed as a fly.
The rods along with fishing flies, are considered to be a traditional local craft of the Kaga region. Although anglers in Scotland and Ireland had been fishing the lochs and loughs for trout with an artificial fly for several generations, the history of stillwater trout fishing in English reservoirs goes back little
A fishing lure is a type of artificial fishing bait, designed to attract a fish's attention. The lure uses movement, vibration and color to bait fish. Many lures are equipped with one or more hooks that are used to catch fish when they strike the lure; some lures are placed to attract fish so a spear can be impaled into the fish or so the fish can be captured by hand. Most lures are attached to the end of a fishing line and have various styles of hooks attached to the body and are designed to elicit a strike resulting in a hookset. Many lures are commercially made but some are hand made such as fishing flies. Hand tying fly. Modern commercial lures are used with a fishing rod and fishing reel but there are some who use a technique where they hold the line in their hands. Handlining is a technique in which the line is held directly in the hands versus being fed through the guides of a fishing rod. Longlining can employ lures to catch fish; when a lure is used for casting, it is continually cast out and retrieved, the retrieve making the lure swim or produce a popping action.
A skilled angler can explore many possible hiding places for fish through lure casting such as under logs and on flats. In early time, fishing lures were made from bronze; the Chinese and Egyptians used fishing rods and lines as early as 2,000 B. C. though most of the first fishermen used handlines. The first hooks were made out of bronze, strong but still thin and less visible to the fish; the Chinese were the first to make fishing line, spun from fine silk. English tackle shops are recorded as selling tin minnows in the middle of the 18th century, realistic imitations of bugs and grubs made from painted rubber appeared as early as 1800. Spoons appear to have originated in Scandinavia in the late 1700s. Early English minnow baits were designed to spin as their attracting action, as exemplified by the “Devon” style lure first produced in quantity by F. Angel of Exeter; the number and variety of artificial baits increased in the mid to late 19th century. The first production lures made in the United States metal spoons and spinners, came on the market in the last half of the 19th century.
The makers included Julio T. Buel, Riley Haskell, W. D. Chapman and Enterprise Manufacturing Company. Modern fishing plugs were first made commercially in the United States in the early 1900s by firms including Heddon in Michigan and Enterprise Mfg. in Ohio. Before this time most fishing lures were made by individual craftsman. Commercial-made lures were based on the same ideas that the individual craftsmen were making but on a larger scale; the fishing lure is either tied with a knot, such as the improved clinch knot, or connected with a tiny safety pin-like device called a "snaps" onto the fishing line, in turn connected to the reel via the arbor. The reel is attached to a rod; the motion of the lure is made by winding line back on to the reel, by sweeping the fishing rod, jigging movements with the fishing rod, or by being pulled behind a moving boat. Exceptions included are artificial flies called flies by fly fishers, which either float on the water surface sink or float underwater, represent some form of insect fish food.
There are many types of fishing lures. In most cases they are manufactured to resemble prey for the fish, but they are sometimes engineered to appeal to a fishes' sense of territory, curiosity or aggression. Most lures are injured, or fast moving fish, they include the following types: A jig is a weighted hook with a lead head opposite the sharp tip. They have a minnow or crawfish or a plastic worm on it to get the fish's attention. Deep water jigs used in saltwater fishing consist of a large metallic weight, which gives the impression of the body of the bait fish, which has a hook attached via a short length of kevlar to the top of the jig; some jigs can be fished in water depths down to 300 metres. Surface lures are known as top water lures and stickbaits, they float and look like fish prey, on top of the water. They can make a popping, burbling, or a buzzing sound, it takes a long time to learn how to use this lure Spoon lures look like a spoon, with a wide rounded end and a narrower pointed end, similar in shape to a concave spearhead.
They flash in the light while darting due to their shape, which attracts fish. LED lures have a battery to attract fish, they use a sometimes strobing pattern, using a combination of colors and LEDs. Plugs are known as crankbaits or minnows; these lures look like fish and they are run through the water where they can move in different ways because of instability due to the bib at the front under the head. Artificial flies are designed to resemble all manner of fish prey and are used with a fly rod and reel in fly fishing. Soft plastic baits are lures made of plastic or rubber designed to look like fish, squid, lizards, frogs and other creatures. Spinnerbait are pieces of wire that are bent at about a 60 degree angle with a hook at the bottom and a flashy spinner at the top. Swimbait is a soft plastic bait/lure; some of these have a tail that makes the lure/bait look like it is swimming when drawn through the water. Fish decoy is a type of lure that traditionally was carved to resemble a fish, small rodent, or an insect that lures in fish so they can be speared.
They are used through the ice by fishermen and by the Inuit people as part of their diet. The Mitchell Museum of the American Indian collection includes Native American fish deco
Lead is a chemical element with symbol Pb and atomic number 82. It is a heavy metal, denser than most common materials. Lead is soft and malleable, has a low melting point; when freshly cut, lead is silvery with a hint of blue. Lead has the highest atomic number of any stable element and three of its isotopes each include a major decay chain of heavier elements. Lead is a unreactive post-transition metal, its weak metallic character is illustrated by its amphoteric nature. Compounds of lead are found in the +2 oxidation state rather than the +4 state common with lighter members of the carbon group. Exceptions are limited to organolead compounds. Like the lighter members of the group, lead tends to bond with itself. Lead is extracted from its ores. Galena, a principal ore of lead bears silver, interest in which helped initiate widespread extraction and use of lead in ancient Rome. Lead production declined after the fall of Rome and did not reach comparable levels until the Industrial Revolution. In 2014, the annual global production of lead was about ten million tonnes, over half of, from recycling.
Lead's high density, low melting point and relative inertness to oxidation make it useful. These properties, combined with its relative abundance and low cost, resulted in its extensive use in construction, batteries and shot, solders, fusible alloys, white paints, leaded gasoline, radiation shielding. In the late 19th century, lead's toxicity was recognized, its use has since been phased out of many applications. However, many countries still allow the sale of products that expose humans to lead, including some types of paints and bullets. Lead is a toxin that accumulates in soft tissues and bones, it acts as a neurotoxin damaging the nervous system and interfering with the function of biological enzymes, causing neurological disorders, such as brain damage and behavioral problems. A lead atom has 82 electrons, arranged in an electron configuration of 4f145d106s26p2; the sum of lead's first and second ionization energies—the total energy required to remove the two 6p electrons—is close to that of tin, lead's upper neighbor in the carbon group.
This is unusual. The similarity of ionization energies is caused by the lanthanide contraction—the decrease in element radii from lanthanum to lutetium, the small radii of the elements from hafnium onwards; this is due to poor shielding of the nucleus by the lanthanide 4f electrons. The sum of the first four ionization energies of lead exceeds that of tin, contrary to what periodic trends would predict. Relativistic effects, which become significant in heavier atoms, contribute to this behavior. One such effect is the inert pair effect: the 6s electrons of lead become reluctant to participate in bonding, making the distance between nearest atoms in crystalline lead unusually long. Lead's lighter carbon group congeners form stable or metastable allotropes with the tetrahedrally coordinated and covalently bonded diamond cubic structure; the energy levels of their outer s- and p-orbitals are close enough to allow mixing into four hybrid sp3 orbitals. In lead, the inert pair effect increases the separation between its s- and p-orbitals, the gap cannot be overcome by the energy that would be released by extra bonds following hybridization.
Rather than having a diamond cubic structure, lead forms metallic bonds in which only the p-electrons are delocalized and shared between the Pb2+ ions. Lead has a face-centered cubic structure like the sized divalent metals calcium and strontium. Pure lead has a silvery appearance with a hint of blue, it tarnishes on contact with moist air and takes on a dull appearance, the hue of which depends on the prevailing conditions. Characteristic properties of lead include high density, malleability and high resistance to corrosion due to passivation. Lead's close-packed face-centered cubic structure and high atomic weight result in a density of 11.34 g/cm3, greater than that of common metals such as iron and zinc. This density is the origin of the idiom to go over like a lead balloon; some rarer metals are denser: tungsten and gold are both at 19.3 g/cm3, osmium—the densest metal known—has a density of 22.59 g/cm3 twice that of lead. Lead is a soft metal with a Mohs hardness of 1.5. It is somewhat ductile.
The bulk modulus of lead—a measure of its ease of compressibility—is 45.8 GPa. In comparison, that of aluminium is 75.2 GPa. Lead's tensile strength, at 12–17 MPa, is low; the melting point of lead—at 327.5 °C —is low compared to most metals. Its boiling point of 1749 °C is the lowest among the carbon group elements; the electrical resistivity of lead at 20 °C is 192 nanoohm-meters an order of magnitude higher than those of other industrial metals. Lead is a superconductor at temperatures lower than 7.19 K.
In optics, the refractive index or index of refraction of a material is a dimensionless number that describes how fast light propagates through the material. It is defined as n = c v, where c is the speed of light in vacuum and v is the phase velocity of light in the medium. For example, the refractive index of water is 1.333, meaning that light travels 1.333 times as fast in vacuum as in water. The refractive index determines how much the path of light is bent, or refracted, when entering a material; this is described by Snell's law of refraction, n1 sinθ1 = n2 sinθ2, where θ1 and θ2 are the angles of incidence and refraction of a ray crossing the interface between two media with refractive indices n1 and n2. The refractive indices determine the amount of light, reflected when reaching the interface, as well as the critical angle for total internal reflection and Brewster's angle; the refractive index can be seen as the factor by which the speed and the wavelength of the radiation are reduced with respect to their vacuum values: the speed of light in a medium is v = c/n, the wavelength in that medium is λ = λ0/n, where λ0 is the wavelength of that light in vacuum.
This implies that vacuum has a refractive index of 1, that the frequency of the wave is not affected by the refractive index. As a result, the energy of the photon, therefore the perceived color of the refracted light to a human eye which depends on photon energy, is not affected by the refraction or the refractive index of the medium. While the refractive index affects wavelength, it depends on photon frequency and energy so the resulting difference in the bending angle causes white light to split into its constituent colors; this is called dispersion. It can be observed in prisms and rainbows, chromatic aberration in lenses. Light propagation in absorbing materials can be described using a complex-valued refractive index; the imaginary part handles the attenuation, while the real part accounts for refraction. The concept of refractive index applies within the full electromagnetic spectrum, from X-rays to radio waves, it can be applied to wave phenomena such as sound. In this case the speed of sound is used instead of that of light, a reference medium other than vacuum must be chosen.
The refractive index n of an optical medium is defined as the ratio of the speed of light in vacuum, c = 299792458 m/s, the phase velocity v of light in the medium, n = c v. The phase velocity is the speed at which the crests or the phase of the wave moves, which may be different from the group velocity, the speed at which the pulse of light or the envelope of the wave moves; the definition above is sometimes referred to as the absolute refractive index or the absolute index of refraction to distinguish it from definitions where the speed of light in other reference media than vacuum is used. Air at a standardized pressure and temperature has been common as a reference medium. Thomas Young was the person who first used, invented, the name "index of refraction", in 1807. At the same time he changed this value of refractive power into a single number, instead of the traditional ratio of two numbers; the ratio had the disadvantage of different appearances. Newton, who called it the "proportion of the sines of incidence and refraction", wrote it as a ratio of two numbers, like "529 to 396".
Hauksbee, who called it the "ratio of refraction", wrote it as a ratio with a fixed numerator, like "10000 to 7451.9". Hutton wrote it as a ratio with a fixed denominator, like 1.3358 to 1. Young did not use a symbol for the index of refraction, in 1807. In the next years, others started using different symbols: n, m, µ; the symbol n prevailed. For visible light most transparent media have refractive indices between 1 and 2. A few examples are given in the adjacent table; these values are measured at the yellow doublet D-line of sodium, with a wavelength of 589 nanometers, as is conventionally done. Gases at atmospheric pressure have refractive indices close to 1 because of their low density. All solids and liquids have refractive indices above 1.3, with aerogel as the clear exception. Aerogel is a low density solid that can be produced with refractive index in the range from 1.002 to 1.265. Moissanite lies at the other end of the range with a refractive index as high as 2.65. Most plastics have refractive indices in the range from 1.3 to 1.7, but some high-refractive-index polymers can have values as high as 1.76.
For infrared light refractive indices can be higher. Germanium is transparent in the wavelength region from 2 to 14 µm and has a refractive index of about 4. A type of new materials, called topological insulator, was found holding higher refractive index of up to 6 in near to mid infrared frequency range. Moreover, topological insulator material are transparent; these excellent properties make them a type of significant materials for infrared optics. According to the theory of relativity, no information can travel faster than the speed of light in vacuum, but this does not mean that the refractive index cannot be lower than 1; the refractive index measures the phase velocity of light. The phase velocity is the speed at which the crests of the wave move and can be faster than the speed of light in vacuum, thereby give a refractive index below 1; this can occur close to resonance frequencies, for absorbing media, in plasmas, for X-rays. In the X-ray regime the refractive indices are