A generator has armature resistance of $0.1 \Omega$ and develops an induced emf of $120 \mathrm{~V}$ when…

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
  1. $120 \mathrm{~V}$
  2. $5 \mathrm{~V}$
  3. $115 \mathrm{~V}$
  4. $70 \mathrm{~V}$

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, $V=e-I R=120-50 \times 0.1=115 \mathrm{~V}$

Asked in: JEE Main 2012 (19 May Online)

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