question_answer

At room temperature, copper has free electron density of\[8.4\times {{10}^{28}}{{m}^{-3}}\]. The electron drift velocity in a copper conductor of cross-sectional area of \[{{10}^{-6}}{{m}^{2}}\] and carrying a current of 5.4 A, will be

A)  \[4\,m{{s}^{-1}}\]          

B)         \[0.4\,m{{s}^{-1}}\]

C)  \[4\,cm\,{{s}^{-1}}\]     

D)         \[0.4\,\,mm\,{{s}^{-1}}\]