What is the minimum resistance which can be made using five resistors each of 1/5 Ω?

Question

(a) 1/5 Ω
(b) 1/25 Ω
(c) 1/10 Ω
(d) 25 Ω

Answer 1

Minimum resistance is observed when they are connected in parallel (you can take it as a thumb rule that the resistance of a group of resistors connected in parallel will be less then the minimum resistance present in the group)

thus net resistance 1/R = 1/R1 + 1/R2 + .... and so it can be calculated to be 1/25

Answer 2

(b) 1/25 Ω is the minimum resistance