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12th Class Physics Alternating Current / प्रत्यावर्ती धारा Question Bank MCQ - Alternating Currents

  • question_answer
              A step down transformer converts transmission line voltage from 11000V to 220V. The primary of the transformer has 6000 turns and efficiency of the transformer is 60%. If the output power is 9 kW, then the input power will be:

    A) 11 kW                          

    B) 12 kW  

    C) 14 kW                          

    D) 15 kW

    Correct Answer: D

    Solution :

    (d) 15 kW Here,     \[{{V}_{P}}=11000\,\,V,\,\,{{V}_{S}}=220\,\,V\] \[{{N}_{P}}=6000,\,\eta =60%:\,{{P}_{0}}=9\,kW=9\times {{10}^{3}}W\] Efficiency, \[\eta =\frac{Output\,power}{Input\,\,power}=\frac{{{P}_{0}}}{{{P}_{i}}}\] \[\therefore {{P}_{i}}=\frac{{{P}_{0}}}{\eta }=\frac{9\times {{10}^{3}}}{60/100}=1.5\times {{10}^{4}}=15\,kW\]


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