Category : Exam Preparation Tips
Resistance
The electrical resistance of a circuit component or device is defined as the ratio of the voltage applied to the electric current which flows through it. If the resistance is constant over a considerable range of voltage,
then Ohm's law, I = V/R,
can be used to predict the behavior of the material. Although the definition above involves DC current and voltage, the same definition holds for the AC application of resistors.Whether or not a material obeys Ohm's law, its resistance can be described in terms of its bulk resistivity. The resistivity, and thus the resistance, is temperature dependent. Over sizable ranges of temperature, this temperature dependence can be predicted from a temperature coefficient of resistance.
Resistivity
The electrical resistance of a wire would be expected to be greater for a longer wire, less for a wire of larger cross sectional area, and would be expected to depend upon the material out of which the wire is made. Experimentally, the dependence upon these properties is a straightforward one for a wide range of conditions, and the resistance of a wire can be expressed as

The factor in the resistance which takes into account the nature of the material is the resistivity . Although it is temperature dependent, it can be used at a given temperature to calculate the resistance of a wire of given geometry.
StudyAdda Provides you:
Log on to http://www.studyadda.com/videos/x-class-science-lectures/electricity/resistance-and-resistivity/1763 .
The study materials and the videos are prepared by Mr.Lalit Sardana(IIT-JEE, AIR 243) & Mrs. Shweta Sardana (Msc.,M.Phil Gold Medalist, AIPMT Trainer),Sardana Tutorials.
You need to login to perform this action.
You will be redirected in
3 sec
