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KCET2020PhysicsCurrent Electricity

A metal rod of length 10 ~cm and a rectangular cross-section of 1 ~cm 1 2 ~cm is connected to a battery across opposite faces. The resistance will be

Options

  1. Amaximum when the battery is connected across 1 ~cm 1 2 ~cm faces
  2. Bmaximum when the battery is connected across 10 ~cm 1 2 ~cm faces
  3. Cmaximum when the battery is connected across 10 ~cm 1 ~cm faces
  4. Dsame irrespective of the three faces

Correct answer

A. maximum when the battery is connected across 1 ~cm 1 2 ~cm faces

Step-by-step solution

Given, length, l=10 ~cm Resistance of metal rod. R= l A i.e., R 1 A Since, among given faces in the options, area is minimum corresponding to face 1 ~cm 1 2 ~cm . Hence, resistance will be maximum when the battery is connected across the face of dimension 1 ~cm 1 2 ~cm .

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