Question

what is resistivity of material of the conductor ? write its formula. Write ranges of the resistivity for good conductors and insulators .​

Answer 1

Answer:

Resistivity is a measure of the resistance of a given size of a specific material to electrical conduction.

Resistivity may also be referred to as the specific electrical resistance, or volume resistivity, although these terms are less widely used.

Although materials resist the flow of electrical current, some are better at conducting it than others.The resistivity is a figure that enables comparisons of the way in which different materials allow or resist current flow.

To enable resistivity figures to be meaningful, specific units are used for resistivity, and there are formulas for calculating it and relating it to the resistance in Ohms for a given size of material.

Materials that conduct electrical current easily are called conductors and have a low resistivity. Those that do not conduct electricity easily are called insulators and these materials have a high resistivity.

The resistivity of different materials plays a major role in selecting the materials used for electrical wire, within many electronic components including resistors, integrated circuits and many more.

Resistivity definition & units

The electrical resistivity of a specimen of a material may also be known as its specific electrical resistance. It is a measure of how strongly a material opposes the flow of electric current.

Resistivity definition:

The resistivity of a substance is the resistance of a cube of that substance having edges of unit length, with the understanding that the current flows normal to opposite faces and is distributed uniformly over them.

The electrical resistivity is the electrical resistance per unit length and per unit of cross-sectional area at a specified temperature.

Resistivity

The SI unit of electrical resistivity is the ohm⋅metre (Ω⋅m). It is commonly represented by the Greek letter ρ, rho.

Although the SI resistivity unit, the ohms metre is generally used, sometimes figures will be seen described in terms of ohms centimetres, Ω⋅cm.

As an example, if a solid cube of material with dimensions of 1 M3 has sheet contacts on two opposite faces which do not introduce any resistance themselves, and the resistance between the contacts is 1 Ω, then the resistivity of the material is said to be 1 &Omega: ˙⋅m.

Resistivity formula / equation

The resistivity of a material is defined in terms of the magnitude of the electric field across it that gives a certain current density. It is possible to devise an electrical resistivity formula.

ρ=EJ

Where:

ρ is the resistivity of the material in ohm metres, Ω⋅m

E is the magnitude of the electric field in volts per metre, V⋅m^-1

J is the magnitude of the current density in amperes per square metre, A⋅m^-2

Many resistors and conductors have a uniform cross section with a uniform flow of electric current. It is therefore possible to create the more specific, but more widely used electrical resistivity formula or equation:

ρ=RAl

Where:

R is the electrical resistance of a uniform specimen of the material measured in ohms

l is the length of the piece of material measured in metres, m

A is the cross-sectional area of the specimen measured in square metres, m^2

It can be seen from the equations that the resistance can be varied by changing a variety of different parameters.

For example, keeping the material resistivity constant, the resistance of the sample can be increased by increasing the length, or decreasing the cross sectional area. It can also be seen from the resistivity equations that increasing the resistivity of the material will increase the resistance assuming the same dimensions. Similarly decreasing the resistivity will decrease the resistance.

Answer 2

Answer:

• Defination:-

• Resistivity, electrical resistance of a conductor of unit cross-sectional area and unit length. A characteristic property of each material, resistivity is useful in comparing various materials on the basis of their ability to conduct electric currents.

• formula :-

• The electrical resistivity is the electrical resistance per unit length and per unit of cross-sectional area at a specified temperature. The SI unit of electrical resistivity is the ohm⋅metre (Ω⋅m). It is commonly represented by the Greek letter ρ, rho.

• range:-

• The resistivity of an exceedingly good electrical conductor, such as hard-drawn copper, at 20° C (68° F) is 1.77 × 10-8 ohm-metre, or 1.77 × 10-6 ohm-centimetre. At the other extreme, electrical insulators have resistivities in the range 1012 to 1020 ohm-metres.

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