what is specific resistivity?
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Specific resistance, or resistivity, is the resistance in ohms offered by a unit volume (the circular-mil- foot or the centimeter cube) of a substance to the flow of electric current. Resistivity is the reciprocal of conductivity. A substance that has a high resistivity will have a low conductivity, and vice versa. Thus, the specific resistance of a substance is the resistance of a unit volume of that substance. Many tables of specific resistance are based on the resistance in ohms of a volume of a substance 1 foot in length and 1 circular mil in cross-sectional area. The temperature at which the resistance measurement is made is also specified. If you know the kind of metal a conductor is made of, you can obtain the specific resistance of the metal from a table. \n\nThe electrical resistivity ρ (rho) of a material is usually defined by the following:\n\nρ=R*A/l\n \nwhere\n\nρ is the static resistivity (measured in ohm metres) \nR is the electrical resistance of a uniform specimen of the material (measured in ohms) \nl is the length of the specimen (measured in metres) \nA is the cross-sectional area of the specimen (measured in square metres) \nElectrical resistivity can also be defined as:\nρ=E/J\n \nwhere\n\nE is the magnitude of the electric field (measured in volts per metre) \nJ is the magnitude of the current density (measured in amperes per square metre)
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A dielectric, or electrical insulator, is a substance that is highly resistant to flow of electric current. and has a relative permittivity greater than unity.
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In electromagnetism:--- \n--------------------------\n, permeability is the degree of magnetization of a material that responds linearly to an applied magnetic field. Magnetic permeability is represented by the Greek letter μ. This term was coined in September, 1885 by Oliver Heaviside. \n\nIn SI units, permeability is measured in henries per metre, or newtons per ampere squared. The constant value μ0 is known as the magnetic constant or the permeability of vacuum, and has the exact value  N·A-2.\n\nSome materials, called ferromagnetic or ferromagnets, are highly magnetic by nature, relative to most materials. They are composed of a large number of very small magnetic units working together called domains. Domains are not always aligned, and they often act against each other to reduce the strength of the net magnetic field.\n\nin Biology:-\n--------------\npermeability means allowing every thing to pass through it. if it so, then everything will be out of the cell and there will be no existance for the cell so, the cell membrane will be semi permeable or selectively permeable means allows the permeability of only selective melecules to pass through it.\n\nA semipermeable membrane, also termed a selectively permeable membrane, a partially permeable membrane or a differentially permeable membrane, is a membrane which will allow certain molecules or ions to pass through it by diffusion and occasionally specialised "facilitated diffusion". The rate of passage depends on the pressure, concentration and temperature of the molecules or solutes on either side, as well as the permeability of the membrane to each solute.\n\nDepending on the membrane and the solute, permeability may depend on solute size, solubility properties, or chemistry. An example of a semi-permeable membrane is a lipid bilayer, on which is based the plasma membrane that surrounds all biological cells. Many natural and synthetic materials thicker than a membrane are also semipermeable. An example of this is the thin film on the inside of an egg.\n\nSemipermeable membranes mostly exist on cells and in one's digestive tract.\n\nVascular permeability ------ characterizes the capacity of a blood vessel wall to pass through small molecules (ions, water, nutrients) or even whole cells (lymphocytes on their way to the site of inflammation). Blood vessel walls are lined by a single layer of endothelial cells. The gaps between endothelial cells (cell junctions) are strictly regulated depending on the type and physiological state of the tissue.
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for an ohmic material:\n\nP=VI\nV=IR\nso\nP=I^2 * R\n\ncheers!
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"Hot" is a very subjective word.  How "hot" is "hot"? 100 degrees C? 500 degrees C?\n\nWhen an object absorbs heat energy its temperature rises, there is no way around it.  But for a given quanity of heat energy (Q) absorbed, some materials will increase in temperature (delta T) more than others.\n\nThe term "Specific Heat" (c) releates the amount of energy needed to raise 1 gram of a substance 1 degree C.\n\nQ = m*c*(delta T)\nHeat enegry = mass of the object * the specific heat * change in temperature\n\nA higher specific heat means that the material will experience a relatively smaller change in temperature for a given amount of heat as compared to another material with a higher specific heat.\n\nUsually, metals tend to have somewhat low specific heats but there are some metals which are higher than others.\nFor instance,...\n-Iron has a specific heat of .444 J/g degree C\n-Copper has a specific heat of .385 J/g degree C\n-Lithium metal (not that this is a practical building material) has a specific heat of 3.582 J/g degree C\n-liquid water's c = 4.184 J/g degree C\n\nmore complete tables of specific heat can heasily be found on the internet.
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IT could be diamagnetic according to electron configuration from Chemistry. But without specific formula I would say your best bet is e nomagnetic.
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Are you asking about thermal conductivity or specific heat?\nAnd why are you not doing the research you should be doing:\nhttp://www.engineeringtoolbox.com/specific-heat-metals-d_152.html\nhttp://www.engineeringtoolbox.com/thermal-conductivity-metals-d_858.html
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wood has very high resistance so the current through it ignored (its effect very small)
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please be more specific
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Water has a very high " specific heat ".  Specific heat is a measurement of how much energy is needed to raise the temperature of a substance. \nHere is a table of a few specific heats:\nhttp://hyperphysics.phy-astr.gsu.edu/hbase/tables/sphtt.html\n\nIf you notice, water is much higher than anything else on that list.\nFor comparison, it would take you 5 times more energy to increase the temperature of water by 1 degree than it would take to increase the temperature of solid granite by 1 degree.  \n\nWater has some very strange properties, but because it is so common, we think nothing of it!
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Specific Heat Capacity\nThe specific heat capacity of a solid or liquid is defined as the heat required to raise unit mass of substance by one degree of temperature. This can be stated by the following equation: \n\nQ= mc(changes of T)\nwhere, \nQ= Heat supplied to substance, \nm= Mass of the substance, \nc= Specific heat capacity, \nT= Temperature rise.
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What type of resistance--thermal, electral, or what?\n\nBoth are generally determined by the bandwidth of free electrons if any are present.  In electrical, it can also deal with impurities in the material.  In thermal, it can have to do with the irregularity of the molecular structure, the density of the solid, and the heat capacity of the molecules.
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V (Voltage) = I (Current) x R (Resistance)\n\nOr (although you probably don't need it):\n\nJ (current density) = sigma (conductivity) x E (electric field)\n\nI always use wikipedia to look up stuff like this, it's very helpful for all kinds of info.
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if u recollect the equation,\n             resistance (r)= pl/A;\n        where p=specific resistivity\n                   l= length\n                   A= cross sectional area \n               Area = pie(3.414) * r2\n                  \n              but diameter is twic the radius.\nhence insulation thickness is dependent on pipe diameter.
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Ohm's Law is always obeyed.\nIf a conductor is non-linear it has a coefficient of resistance - thermal, pressure, tensile, even voltage-dependent.\nMeasure the current thru it and the voltage across it and you have the instantaneous resistance at the time of measurement.\nThe law stands, but the result may not be static.
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1. Eelctrical 'restistance' is directly proportional to the amplitude of molecular vibrations within the matellic substance (Usually). Since the Electricity is flow of electrons, these (Vibrating molecules) will be frequently colliding with electrons and offer resistance to the flow. This is nothing but the electrical resistance.  \n2. The Molecular 'vibrational amplitude' is proportional to the heat within the substance. (Hotter the metal more the amplitude of molecular vibrations)\n3. Naturally for the reasons above, in cold metals the vibrational amplitudes of the molecules are less, and therefore, the electrical restistance too. Hence in your simple term ' The electric move faster in cold metals , .
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Consider a conductor of uniform area of crossection A, length L. Let resistivity of conductor be S and resistance of material to current be R.\n\n  Then,  R = SL/A\n\n     Multiply and divide by mass of conductor say m and L\n\n          R = SL*L*m/L*A*m\n\n But L * A  = Volume = V\nAnd m / V   = Density = d\n\n  Hence,  R =  S*L*L*d/m\n          S =  (m*R/L*L)/d\n\nThus, Resistvity (S) is inversely proportional to density(d) when other quantities are kept constant.