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In the circuit shown in the figure. A , R 3 is a variable resistance As the value R 3 is changed, current I though the cell varies as shown. Obviously, the variation is asymptotic, i.e. I → 6 A as R 3 → ∞ . Resistances R 1 and R 2 are, respectively

Options

  1. A4 Ω , 2 Ω
  2. B2 Ω , 4 Ω
  3. C2 Ω , 2 Ω
  4. D1 Ω , 4 Ω

Correct answer

C. 2 Ω , 2 Ω

Step-by-step solution

For R 3 = 0 , I = 9   A (from the graph).In this situation, the circuit can be drawn as shown in figure A . [current through R 2 will be zero because we have a short circuit R 3 = 0 across R 2 ] Here I = 36 R 1 + R 2 = 9   A or R 1 + R 2 = 4   Ω ...(1) current will not flow through R 3 , it will be open circuit. In this situation, the circuit can be drawn as shown figure B . Figure (B) Now I = 36 R 1 + 2 R 2  = 6   A (given) ∴   R 1 + 2 R 2 = 6   Ω ...(2) from Eqs.

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