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JEE Main20211 Sep 2021Evening ShiftPhysicsCurrent ElectricityActual

Two resistors R 1 = ( 4 ± 0 . 8 ) Ω and R 2 = ( 4 ± 0 . 4 ) Ω are connected in parallel. The equivalent resistance of their parallel combination will be :

Options

  1. A( 4 ± 0 . 4 )   Ω
  2. B( 2 ± 0 . 4 )   Ω
  3. C( 4 ± 0 . 3 )   Ω
  4. D( 2 ± 0 . 3 )   Ω

Correct answer

D. ( 2 ± 0 . 3 )   Ω

Step-by-step solution

Δ R R 2 = Δ R 1 R 1 2 + Δ R 2 R 2 2 Δ R = R 2 Δ R 1 R 1 2 + Δ R 2 R 2 2 = 2 2 0 . 8 4 2 + 0 . 4 4 2 = [ 0 . 2 + 0 . 1 ] = 0 . 3 R net  = R + Δ R = 2 ± 0 . 3

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