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A d.c. main supply of e.m.f. 220 V is connected across a storage battery of e.m.f. 200 V through a resistance of 1 Ω . The battery terminals are connected to external resistance R . The minimum value of R , so that a current passes through the battery to charge it is:

Options

  1. A9   Ω
  2. B7   Ω
  3. C11   Ω
  4. D0

Correct answer

C. 11   Ω

Step-by-step solution

Given, emf of cell E = 200 V Resistance = 1 Ω D. C. main supply voltage V = 220V External resistance R = ? r = E - V V R 1 = 20 220 × R ∴    R = 11 Ω

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