A cylindrical conductor of length `l` and uniform area of cross-section `A` has resistance `R`. Another conductor of length `2 l` and resistance `R` of the same material has area of cross-section :

Options

A. `A//2`
B. `3A//2`
C. 2A
D. 3A

Answer

C

Explanation

Resistivity of the conductor in the first case, `rho=(RA)/(I)`
Resistivity of the conductor in second case,
`rho=(RA)/(2I)`
Since, both conductors are of same material and are at same temperature, so the resistivity of both conductor will be same. Therefore, from equations, (i) and (ii), we have :
`rarr(RA)/(I)=(RA)/(2I)`
`rarrA=2A`