• # question_answer A constant voltage is applied between two ends of a uniform conducting wire. If both the length and radius of the wire are doubled A) the heat produced in the wire will be doubled B) the electric field across the wire will be doubled C) the heat produced will remain unchanged D) the electric field across the wire will remain unchanged

 $R=\frac{\rho l}{A}=\frac{\rho l}{\pi {{r}^{2}}}$ If l and r are doubled, R will become one half. Thus heat produced per second will become twice because $H={{V}^{2}}/R$. Also, since$E=\frac{V}{l}$, E will become one half. hence the correct choice is A.