question_answer

                The specific resistance of a conductor increases with:                                                                    

A)                 increase in temperature                              

B)                 increase in cross-sectional area

C)                 decrease in length                                          

D)                 decrease in cross-sectional area

Correct Answer: A

Solution :

                The specific resistance (resistivity. of a metallic conductor nearly increases with increasing temperature as shown in figure This is because, with the increase in temperature the ions of the conductor vibrate with greater amplitude, and the collision between electrons and ions become more frequent, over a small temperature range (up to 100oC). The resistivity of a metal can be represented approximately by the equation.                                 \[{{\rho }_{t}}={{\rho }_{0}}\,(1+\alpha t)\]                 The factor \[\alpha \] is called the temperature coefficient of resistivity.