Figure (a), (b) and (c) show three cylindrical copper conductors alongwith their face areas and length. Which of the conductors will have highest resistance and why?

Explanation

(i) `R_(a)= rho(L)/(A)`
(ii) `R_(b)= rho ((2L)/(A//2))= rho((4L)/(A))= 4R_(a)`
(iii) `R_(c)= rho ((L)/(2(2A)))= (1)/(4)rho((L)/(A))= (1)/(4)R_(a)`
Hence, `R_(b) gt R_(a) gt R_(c)` Thus, the conductor (b) will have the highest resistance.