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BVP Medical BVP Medical Solved Paper-2008

  • question_answer
    An electric motor runs on DC source of emf 200 V and draws a current of 10 A. If the efficiency be 40% then the resistance of armature is

    A)  2 \[\Omega \]                                  

    B) 8 \[\Omega \]

    C)  12 \[\Omega \]                                

    D)  16 \[\Omega \]

    Correct Answer: C

    Solution :

                    Input power \[=VI=200\times 10\] \[=2000\text{ }W,\] Output power \[=\frac{40}{100}\times 2000\]                 \[=800W\] Power loss in heating the armature                 \[=2000-800\]                 \[=1200W\] \[\therefore \]  \[{{I}^{2}}R=1200\] or            \[R=\frac{1200}{{{I}^{2}}}\]                 \[=\frac{1200}{10\times 10}\] or            \[R=12\Omega \]


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