Question

Two resistors when connected in parallel have an equivalent of 2Ω and when in series of 9Ω The values of the two resistors are.

(A) 2Ω and 9Ω

(B) 3Ω and 6Ω

(C) 4Ω and 5Ω

(D) 2Ω and 7Ω

Answer 1

The correct option (B) 3Ω and 6Ω

Explanation:

Let resistance be R1 & R2

R1 + R2 = 9 (1)

{(R1 ∙ R2)/(R1 + R2)} = 2

∴ R1 ∙ R2 = 2(R1 + R2) = 2 × 9 = 18

R1 = (18/R2)

from (1), R2 + (18/R2) = 9

R22 + 18 – 9R2 = 0

R2 = 3Ω or 6Ω