Question

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 find the ratio R/R' .

Answer 1

The resistance wire when cut into 5 equal parts,resistance of one part=R/5
The wires are connected in parallel hence
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
The ratio,
R/R'
=R/(R/25)
=25:1
Hope it helped you..