Q84 / 90 · JEE Main 2012 (19 May Online) · Physics

A generator has armature resistance of $0.1 \Omega$ and develops an induced emf of $120 \mathrm{~V}$ when driven at its rated speed. Its terminal voltage when a current of $50 \mathrm{~A}$ is being drawn is

  • A
    $120 \mathrm{~V}$
  • B
    $5 \mathrm{~V}$
  • Correct answer
    C
    $115 \mathrm{~V}$
  • D
    $70 \mathrm{~V}$

Solution

Armature resistance $R=0.1 \Omega$ Induced emf, $e=120 \mathrm{~V}$ Current drown, $I=50 \mathrm{~A}$ We know that, $e=V+I R$ or, $V=e-I R=120-50 \times 0.1=115 \mathrm{~V}$

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

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