The equivalent resistance of two resistors connected in series is 6 Ω and their parallel equivalent resistance is 4/3Ω. What are the values of resistances?

Options

(a) 4Ω,6Ω
(b) 8Ω,1Ω
(c) 4Ω,2Ω
(d) 6Ω,2Ω

Correct Answer:

4Ω,2Ω

Explanation:

Let the values of resistance be R₁ and R₂, respectively.
When R₁ and R₂ resistance are series, then
R₁ + R₂ = 6 (according to question) ——(i)
When R₁ and R₂ resistance are parallel, then
R₁R₂ / R₁+R₂ = 4 / 3 ——(ii)
From the equation (i), we get
R₁R₂ / 6 = 4 / 3 ⇒ R₁R₂ = 4 × 3 ⇒ R₁R₂ = 8 —–(iii)
We know that,
R₁ – R₂ = √[(R₁ + R₂)² – 4R₁R₂] = √[36 – 4 × 8] = √4 = 2
From equation (i) and (iv), we get
R₁ = 4 Ω, R₂ = 2 Ω