Definition of Electrical Resistivity
Page 1 of 1 • Share •
Definition of Electrical Resistivity
Electrical resistivity ρ (Greek: rho) is defined by, where ρ is the static resistivity (measured in ohmmetres, Ωm) E is the magnitude of the electric field (measured in volts per metre, V/m);AZ70XX J is the magnitude of the current density (measured in amperes per square metre, A/m˛). Many resistors and conductors have a uniform cross section with a uniform flow of electric current and are made of one material. (See the diagram to the right.) In this case, the above definition of ρ leads to: AZ70XX where R is the electrical resistance of a uniform specimen of the material (measured in ohms, Ω) is the length of the piece of material (measured in metres, m)AZV99 A is the crosssectional area of the specimen (measured in square metres, m˛). The reason resistivity has the dimension units of ohmmetres can be seen by transposing the definition to make resistance the subject: The resistance of a given sample will increase with the length, but decrease with greater crosssectional area. Resistance is measured in ohms. Length over area has units of 1/distance. To end up with ohms, resistivity must be in the units of "ohms × distance" (SI ohmmetre, US ohminch).
In a lownoise amplifier or preamp the noise characteristics of a resistor may be an issue. In a hydraulic analogy, increasing the crosssectional area of a pipe reduces its resistance to flow, AZV99and increasing the length increases resistance to flow (and pressure drop for a given flow). Practical resistors include a series inductance and a small parallel capacitance; these specifications can be important in highfrequency applications.
http://www.seekic.com/icdata/AZV99.htmlAZ70XXAZV99
In a lownoise amplifier or preamp the noise characteristics of a resistor may be an issue. In a hydraulic analogy, increasing the crosssectional area of a pipe reduces its resistance to flow, AZV99and increasing the length increases resistance to flow (and pressure drop for a given flow). Practical resistors include a series inductance and a small parallel capacitance; these specifications can be important in highfrequency applications.
http://www.seekic.com/icdata/AZV99.htmlAZ70XXAZV99
阿米1 Number of posts : 3
Religion : NonMuslim
Department : Electrical
Session : 2000
Residence Status : Boarder
Registration date : 20110513
Similar topics
» Definition of procurement unit
» What is the acceptable definition of "Similar Contract'
» Post Disqualification Procedure
» Jeudi 2 décembre  WikiLeaks
» SuperEarth at HD 97658, Neptune at GJ 785
» What is the acceptable definition of "Similar Contract'
» Post Disqualification Procedure
» Jeudi 2 décembre  WikiLeaks
» SuperEarth at HD 97658, Neptune at GJ 785
Page 1 of 1
Permissions in this forum:
You cannot reply to topics in this forum

