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The length of a wire of a potentiometer is 100 ~cm , and the e.m.f. of its standard cell is E volt. It is employed to measure the e.m.f of a battery whose internal resistance is 0.5 . If the balance point is obtained at l =30 cm from the positive end, the e.m.f. of the battery is

Options

  1. A30 E 100.5
  2. B30 E (100-0.5)
  3. C30( E -0.5 i ) 100 , where i is the current in the potentiometer wire
  4. D30 E 100

Correct answer

D. 30 E 100

Step-by-step solution

Potential R R length Potential difference l

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