Search results
Results from the WOW.Com Content Network
Electrical resistivity (also called volume resistivity or specific electrical resistance) is a fundamental specific property of a material that measures its electrical resistance or how strongly it resists electric current. A low resistivity indicates a material that readily allows electric current.
Also called chordal or DC resistance This corresponds to the usual definition of resistance; the voltage divided by the current R s t a t i c = V I. {\displaystyle R_{\mathrm {static} }={V \over I}.} It is the slope of the line (chord) from the origin through the point on the curve. Static resistance determines the power dissipation in an electrical component. Points on the current–voltage ...
Contact resistance values are typically small (in the microohm to milliohm range). Contact resistance can cause significant voltage drops and heating in circuits with high current. Because contact resistance adds to the intrinsic resistance of the conductors, it can cause significant measurement errors when exact resistance values are needed.
The electrical resistance of a uniform conductor is given in terms of resistivity by: [40] = where ℓ is the length of the conductor in SI units of meters, a is the cross-sectional area (for a round wire a = πr 2 if r is radius) in units of meters squared, and ρ is the resistivity in units of ohm·meters.
Sheet resistance is a special case of resistivity for a uniform sheet thickness. Commonly, resistivity (also known as bulk resistivity, specific electrical resistivity, or volume resistivity) is in units of Ω·m, which is more completely stated in units of Ω·m 2 /m (Ω·area/length).
In the figure, R x is the fixed, yet unknown, resistance to be measured. R 1, R 2, and R 3 are resistors of known resistance and the resistance of R 2 is adjustable. The resistance R 2 is adjusted until the bridge is "balanced" and no current flows through the galvanometer V g.
Joule immersed a length of wire in a fixed mass of water and measured the temperature rise due to a known current flowing through the wire for a 30 minute period. By varying the current and the length of the wire he deduced that the heat produced was proportional to the square of the current multiplied by the electrical resistance of the ...
Resistance wire is wire intended for making electrical resistors (which are used to control the amount of current in a circuit). [1] It is better if the alloy used has a high resistivity , since a shorter wire can then be used.