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JEE Main20208 Jan 2020Morning ShiftPhysicsCurrent ElectricityActual

The length of a potentiometer wire is 1200 c m and it carries a current of 60 m A For a cell of e m f 5 V and internal resistance of 20 Ω the null point on it is found to be at 1000 c m The resistance of whole wire is:

Options

  1. A80 Ω
  2. B120 Ω
  3. C60 Ω
  4. D100 Ω

Correct answer

D. 100 Ω

Step-by-step solution

Potential gradient = 5 1000 = V P 1200 V P = 6   V And R P = V P I = 6 60 × 10 - 3 = 100   Ω

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