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Manipal Medical Manipal Medical Solved Paper-2009

  • question_answer
    An electric motor operates on a 50 V supply and a current of 12 A. If the efficiency of the motor is 30%, what is the resistance of the winding of the motor?

    A)  \[6\,\Omega \]              

    B)  \[4\,\Omega \]

    C)  \[2.9\,\Omega \]           

    D)  \[3.1\,\Omega \]

    Correct Answer: C

    Solution :

    \[I=\frac{E-e}{R}\]                            ...(i) and    \[\eta \times 100=\left( \frac{e}{E} \right)\times 100\]                       ...(ii) \[\therefore \] \[30=\frac{e}{50}\times 100\]                  [from Eqs. (ii)] \[\Rightarrow \] \[e=15V\] Thus,     \[R=\frac{50-15}{12}=2.9\,\Omega \]


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