Question

When ‘n’ equal resistors connected in series the effective resistance becomes 18 Ω and when connected in parallel it becomes 2 Ω. Find the number of resistors and the value of resistance

Answer 1

Answer:

let the resistors be a(since all are equal)

therefore Ps=a+a+a......+a=18

na=18(since there are n resistors)

Pp=1/a+1/a+......+1/a=2

n/a=2

by substituting n/a=2 as n=2a in na=18

(2a)a=18

a^2=9

a=3

therefore n/a=2

n/3=2

n=6

therefore there are(n) 6 resistors with resistance(a)=3