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.
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.
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.
because there properties are beter than metals
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.
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.
The resistivity of graphite magnitude is substantially higher than common metal alloys such as aluminum, silver and copper.
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.
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.
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
Because alloys have better mechanical properties, better resistance to corrosion, to high temperatures, the crystalline structure is more stable etc.
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.
Good conductors of electricity. Examples all metals and their alloys.
alloys are used in heating appliances to increase the heat conductivity in the electrical heating devices.
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.
Cast alloys are alloys that are cast in a cast.
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.
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.
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
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.
alloys are found in Iraq
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.
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 :)
There are many more than two types of metal alloys. There are aluminum alloys, titanium alloys, magnesium, iron (steel); there are alloys of pretty much any metal out there
metal coatings, catalysts, components for instruments, machines, etc., alloys, hydrogen absorbent, electrical batteries, etc.