`n` conducting wires of same dimensions but having resistivities 1,2,3,….n are connected is series. The equivalent resistivity of the combination is

Options

A. `(n(n+1))/(2)`
B. `(n+1)/(2)`
C. `(n+1)/(2n)`
D. `(2n)/(n+1)`

Answer

B

Explanation

`R=R_(1)+R_(2)+…R_(n)`
`(rho(nl))/(A)=l(l)/(A)+2(l)/(A)+….+n(l)/(A)`
`rhon=1+2+3+…+n`
`rhon=(n(n+1))/(2)=(n+1)/(2)`