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MHT CET202019 Oct 2020Morning ShiftPhysicsCurrent ElectricityActual

In meter-bridge experiment a resistance of 18 is connected in left gap and an unknown resistance R is connected in right gap. The null point is obtained at ' ₁ ^ from left end. If unknown resistance is replaced by ( R 3 ) , the null point is obtained at 1 5 ₁ . The unknown resistance is

Options

  1. A9
  2. B36
  3. C18
  4. D27

Correct answer

C. 18

Step-by-step solution

(A) 18 ₁ = R 100- ₁ ...(1) 18 1.5 ₁ = R / 3 100-1.5 ₁ = R 300-4.5 ₁ ...(2) Dividing Eq. (1) by Eq. (2) and solving, ₁=50 ~cm Substituting this value of ₁ in Eq. (1) we get R =18

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