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Answered 2007-10-22 22:44:38

Resistance is due to scattering of conduction electrons. A metallic crystal can be viewed simplistically as a periodic array of ions with a cloud of delocalised conduction elections. The electrons do not scatter of the ions themselves because the crystal is periodic. There are two significant causes of scattering: 1. scattering off vibrations of the atomic lattice (phonons). This contribution to the resistivity is proportional to temperature. 2. scattering off defects in the crystal. At low temperature, this is the cause of a finite 'residual resistivity'. The two terms add linearly Rtotal = R1(T) + R2 Cold working a metal will introduce defects and thus lead to an increase in R2. Conversely, annealling the metal at high temperature will remove defects and reduce the residual resistivity.

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Why does alloys have high resistivity?

It is not a right perception to think that alloys have high resistivity. Alloys can have high resistivity or low resistivity than the actual elements. You might be thinking that alloys have high resistivity as many resistors are made of alloys. But by altering the composition of elements, we can also make an alloy of very low resistivity.


What are effect of alloying on resistivity of metal?

The presence of impurities and alloying elements decrease the electrical conductivity of most of the metals.. Hence thereby the alloying of metals increase the resistivity of metals and decrease its electrical conductivity.. But rarely.,, certain magnetic alloys increase its conductivity.



Why in an inductor does the resistance rise when the temperature increases?

Temperature affects the resistivity of materials which, in turn, affects their resistance. For pure metal conductors, their resistance increases with temperature. As an inductor is often made from a coil of copper wire, its resistance will increase whenever its temperature increases. If it is important for the resistance to remain constant over a wide variation of temperature, then alloys, such as constantin, are used instead of copper. These alloys maintain an approximately-constant resistance over a wide range of temperatures.


What is the resistivity of nichrome?

There are different compositions of nichrome, with different proportions of nickel and chromium. Resistivity of the various alloys ranges between 1.0 x 10-6 to 1.5 x 10-6 ohm-meter.


Why graphite is not used to make wires?

The resistivity of graphite magnitude is substantially higher than common metal alloys such as aluminum, silver and copper.


Why does converting pure metals into alloys often increases the strength of the product?

Converting pure metals into alloys usually increases the strength of metals. This is because when two pure metals are made into an alloy, a chemical reaction which is harder to break usually occurs.


Why does resistance decrease when voltage and current increase?

actually according to ohm's law at a constant temperature I directly proportional to v. there by keeping a const. 1/R we get v=IR. RESISTANCE depends on the physical parameters. R=s L/A. when the voltage rises there exists a voltage difference which increases there by increases the temperature rise occures which agitates the molecules of the resistor . this excitation causes the free movement of molecules which in turn increases the conduction and a fall in resistance..........AnswerThe simple answer is that it is temperature change that affects resistance, not the increase in current itself.The resistance of a conducting material (any material, come to that) is affected by its length, cross-sectional area, and resistivity. As resistivity is affected by temperature, then resistance is indirectly affected by temperature -how much depends upon the type of material from which the conductor is manufactured.For pure metal conductors, resistivity tends to increasewith temperature. So, if an increasing current flowing through such a conductor causes its temperature to rise, then its resistivity increases, causing its resistance to rise. For example, the resistance of the tungsten filament of an incandescent lamp increases quite markedly between its 'cold' temperature and its 'hot' (operating) temperature.Some alloys are manufactured so that their resistivity (and, therefore, their resistance) remains constant over a wide range of temperature variations. The resistivity of insulators, on the other hand, falls with an increase in temperature, causing their resistance to fall with an increase in temperature -in fact, a high temperature is the major cause of insulation failure.


Alloys are used in electrical heating devices rather than pure metals. Give reason.?

Alloys are used rather than pure metals in electrical heating devices since they have low electrical conductivity and also a low melting point. Usually the alloys don't have a single melting point; they have a range of melting points. The temperature at which melting begins is called the SOLIDUS and the temperature at which melting is complete is called the LIQUIDUS.Student


What is cupronickel's properties?

Cupronickel is widely used for marine applications due to their excellent resistance to seawater corrosion, high resistance to biofouling, and good fabricability. Copper rich alloys are ductile, can be hardened only by cold working, good corrosion resistance, good strength, low temperature co-efficient of electrical resistance. The nickel content in these alloys also enables them to retain their strength at elevated temperatures compared to copper alloys without nickel.


What are 2 different alloys and explain what they are made out of?

1 Alloys of magnesium2 Alloys of aluminum3 Alloys of potassium4 Alloys of iron5 Alloys of cobalt6 Alloys of nickel7 Alloys of copper8 Alloys of gallium9 Alloys of silver10 Alloys of tin11 Rare earth alloys12 Alloys of gold13 Alloys of mercury14 Alloys of lead15 Alloys of bismuth16 Alloys of zirconiumBUT I AM SURE WHAT THEY ARE MADE OF I HOPE THIS HELPS :)


Why alloys are used in electrical heating device rather than pure metals?

Because alloys have better mechanical properties, better resistance to corrosion, to high temperatures, the crystalline structure is more stable etc.


Objects that let electrical charge move through them are called?

Good conductors of electricity. Examples all metals and their alloys.


Name 10 alloy metals?

The below is according to Wikipedia.1 Alloys of aluminium2 Alloys of bismuth3 Alloys of cobalt4 Alloys of copper5 Alloys of gallium6 Alloys of gold7 Alloys of indium8 Alloys of iron9 Alloys of lead10 Alloys of magnesium11 Alloys of mercury12 Alloys of nickel13 Alloys of potassium14 Alloys of plutonium15 Rare earth alloys16 Alloys of silver17 Alloys of titanium18 Alloys of tin19 Alloys of uranium20 Alloys of zinc21 Alloys of zirconiumFor the source and more detailed information concerning your request, click on the related links section (Answers.com) indicated directly below this answer section.


Why are alloys constantan and Manganin used to make standard resistors?

They are used to make standard resistors because 1)they have high value of resistivity.2)temperature cofficient of resistance is less.3)they are least affected by temperature.


Types of alloys?

Alloys are a combination of two or more materials that can be metallic and non-metallic. Different types of alloys are stainless steel alloys, aluminum alloys, and brass alloys. Other types of alloys are copper, cobalt, zinc, gold, and lead alloys.


What is cast alloys?

Cast alloys are alloys that are cast in a cast.


How is the resistance of a metallic conductor affected by variation in temperature?

In general, pure metal conductors increase in resistance as their temperature increases. This is not necessarily true for alloys, as some alloys are manufactured to have an approximately constant resistance over a wide range of temperatures.


Is a magnet an isulator?

That might depend on what material the magnet is made from, but usually magnets are made from metals or alloys, i.e., electrical conductors.


What do they put copper in?

pipes It is also used in electrical wiring & electrical conductors, heat sinks, roofing, flashing, various alloys such as brass and bronze, gold alloys, sculpture, soft faced hammers, and some types of engine head gaskets. Old pennies had a high percentage copper. New pennies are copper plated zinc.


Difference between ferrous alloys and non-ferrous alloys?

compositionally a ferrous alloy contains Fe in some form - so steels, stainless steels are Ferrous alloys Non Ferrous alloys include copper alloys such as brass and bronze; aluminum alloys and titanium alloys for aerospace applications and many others. These alloys DO NOT contain iron


Will lead conduct electricity?

Yes, lead does conduct electricity, but it is a poor conductor. Silver is the best electrical conductor of any known metal. At 20 °C it has 15.87 nΩ·m electrical resistivity. Copper is the second best conductor, at 16.78 nΩm. Gold comes in third, at 22.14 nΩm. Aluminum is next at 26.50 nΩm. Lead is way down the line at 1.29 µΩm. As electrical resistivity is the inverse of electric conductivity, it follows that the more resistance something has the less conductive it is. Lead is a poor electrical conductor. n or nano = 10^-9, which is one billionth or .0000000001 µ or micro = 10^-6, which is one millionth, or .0000001 Lead is used in building construction, lead-acid (car) batteries, bullets shots, weights, pewters, fusible alloys and as a radiation shield. Lead has the highest atomic number of all of the stable elements. Lead is potent neurotoxin and is poisonous to mammals in that it damages the nervous system and causes both blood and brain disorders. These numbers are from: David R. Lide, CRC Handbook of Chemistry and Physics, 84th Edition. CRC Press. Section 12, Properties of Solids; Electrical Resistivity of Pure Metals.


Whether the resistivity of copper or its alloy is greater?

Copper alloy is often used in preference to pure copper due to its hardenss. Pure metals are usually soft and can be cut easily. They are not suitable for making any hard bodies. Therefore, alloys are used.


What are the uses of ferro alloys and how they are used?

Ferroalloy refers to various alloys of iron with a high proportion of one or more other element, manganese or silicon for example. It is used in the production of steels and alloys as a raw material. Ferroalloys are used to add characteristics of anti-corrosion and deoxidisation. They are a raw material to produce chemicals, welding electrodes and electrical equipment.


Where are alloys found?

alloys are found in Iraq


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