The resistance of two conducters in series is 40 ohm and their resistance becomes 7.5 ohm when connected in parallel.Find the resistance of the two individual conductors....{PLEASE SOLVE THIS QUESTION BY THE METHOD OF QUADRATIC EQUATION}

Asked by Pulkit | 13th May, 2012, 10:38: AM

Expert Answer:

say two resistances are r1 &r2.
r1+r2=40 from the series formula
(r1 xr2)/(r1+r2)=7.5  from the formula of parallel res
so from equ 1 and 2:
r1 xr2=7.5x40=300
r1=300/r2
put this in equ 1:
300/r2  + r2 =40
r22-40x r2+300=0
(r2-30) (r2-10)=0
r2=30 or 10
simlarly r1=10 or 30

Answered by  | 13th May, 2012, 07:29: PM

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