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NEET2015PhysicsCurrent ElectricityActual

Two metal wires of identical dimensions are connected in series. If v 1 and v 2 are the conductivities of the metal wires respectively, the effective conductivity if the combination is:

Options

  1. Aσ 1 + σ 2 2 σ 1 σ 2
  2. Bσ 1 + σ 2 σ 1 σ 2
  3. Cσ 1 σ 2 σ 1 + σ 2
  4. D2 σ 1 σ 2 σ 1 + σ 2

Correct answer

D. 2 σ 1 σ 2 σ 1 + σ 2

Step-by-step solution

R e c = l σ 1 A + l σ 1 A = l e q σ e q A e q 2 l σ e q A = l A σ 1 + σ 2 σ 1 σ 2 σ e q = 2 σ 1 σ 2 σ 1 + σ 2

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