A piece of wire of resistance R is cut into five equal parts. These parts are then connected in parallel. R If the equivalent resistance of this combination is R', then the ratio `(R)/(R')` is:

Explanation

Resistance of this wire, `R= rho(l)/(A)`
Resistance of a piece of length `(l)/(5)= rho (l)/(5A)= (R)/(5)`
The equivalent resistance of the 5 wires in parallel is R.. Then
`(1)/(R.)= (1)/(R//5)+(1)/(R//5)+(1)/(R//5)+(1)/(R//5)+(1)/(R//5)`
`(1)/(R.)= (5)/(R)+(5)/(R)+(5)/(R)+(5)/(R)+(5)/(R)`
`(1)/(R.)= (25)/(R)`
`(R)/(R.)= 25`
Hence, the correct answer is (d).