Question

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

Answer 1

Resistance of a piece of wire is proportional to its length. A piece of wire has a resistance R. The wire is cut into five equal parts. Therefore, resistance of each part =R/5 
All the five parts are connected in parallel. 
?equivalent resistance (R') is given as 


Answer 2

resistance of one piece will be r/5 and 1/r' = 5/r+5/r+5/r+5/r+5/r= 25/r therefore ratio is 25/r x r = 25:1or 25