Q18 / 256 · NTA Abhyas (NEET) 2020 · Physics · Current Electricity

An electric current is passed through a circuit containing two wires of the same material, connected in parallel. If the lengths and radii of the wires are in the ratio of 4/3 and 2/3, then the ratio of the currents passing through the wire will be

  • A
    3
  • B
    8/9
  • C
    2
  • Correct answer
    D
    1/3

Solution

V = I 1 R 1 = I 1 ρ ℓ 1 π r 1 2

V = I 2 R 2 = I 2 ρ ℓ 1 π r 2 2

⇒ I 1 R 1 = I 2 R 2

⇒ I 1 I 2 = R 2 R 1 = ρ ℓ 2 π r 2 2 × π r 1 2 ρ ℓ 1 = ℓ 2 ℓ 1 r 1 r 2 2 = 3 4 × 2 3 2 = 1 3

Hence, the correct answer is option: 'D'.

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