Job Training and Career Qualifications | Metal and Alloys

Why electrical resistivity of metals alloys increases with degree of cold working?

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.

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 Alloys of metals have greater resistivity than their constituents?

because there properties are beter than metals

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…

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…

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.

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.

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.

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

1 Alloys of magnesium 2 Alloys of aluminum 3 Alloys of potassium 4 Alloys of iron 5 Alloys of cobalt 6 Alloys of nickel 7 Alloys of copper 8 Alloys of gallium 9 Alloys of silver 10 Alloys of tin 11 Rare earth alloys 12 Alloys of gold 13 Alloys of mercury 14 Alloys of lead 15 Alloys of bismuth 16 Alloys of zirconium BUT I AM SURE WHAT THEY ARE MADE OF I HOPE…

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.