Define the resistivity of a material if a wire of radius 0.1cm and length 5cm has resistance 7 ohm then calculate it's resistivity
Answers
Answer:
14π×10∧-5 ohm.m
Explanation:
it has been stated that the resistance R of any material at constant temperature is varying inversely with it's cross sectional area A and directly with its length.
R = kL/A , k is the resistivity .
k = RA/L = 7π×10∧-6/5×10∧-2 = 14π×10∧-5 ohm.m
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.
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
Semiconductors
Variable*
Superconductors
0
* The level of conductivity of semiconductors is dependent upon the level of doping. With no doping they appear almost like an insulator, but with doping charge carriers are available and the resistivity falls dramatically. Similarly for electrolytes, the level of resistivity varies widely.
Check out more details in our . . . . table of the resistivity of different materials.
Practical implications of resistivity
The resistivity of materials is important as it enables the right materials to be used into e right instances.
Materials used as conductors, for example in wire need to be able to have a low level of resistivity. This means that for a given cross sectional area, the resistance of the wire will be low.
As an example, copper is a good conductor as it provides a low
Explanation:
Sodium and fluorine bonding ionically to form sodium fluoride. Sodium loses its outer electron to give it a stable electron configuration, and this electron enters the fluorine atom exothermically. The oppositely charged ions are then attracted to each other. The sodium is oxidized, and the fluorine is reduced.
File:16. Реакција меѓу силно оксидационо и редукционо средство.webmPlay media
Demonstration of the reaction between a strong oxidising and a reducing agent. When a few drops of glycerol (mild reducing agent) are added to powdered potassium permanganate (strong oxidising agent), a violent redox reaction accompanied by self-ignition starts.
Redox (short for reduction–oxidation reaction) (pronunciation: /ˈrɛdɒks/ redoks or /ˈriːdɒks/ reedoks[1]) is a type of chemical reaction in which the oxidation states of atoms are changed. Redox reactions are characterized by the transfer of electrons between chemical species,