JEE Main & Advanced Physics Alternating Current / प्रत्यावर्ती धारा Question Bank Self Evaluation Test - Alternating Current

  • question_answer
    Figure shows an iron - cored transformer assumed to be 100% efficient. The ratio olf the secondary turns to the primary turns is 1:20.     A 240 V ac supply is connected to the primary coil and a 6 W resistor is corrected to the secondary coil. What is the current in the primary coil?

    A) 0.10 A

    B) 0.14 A

    C) 2 A  

    D) 40 A

    Correct Answer: A

    Solution :

    [a] The equivalent primary load is \[{{R}_{1}}={{\left( \frac{{{N}_{1}}}{{{N}_{2}}} \right)}^{2}}\,{{R}_{2}}={{\left( \frac{20}{1} \right)}^{2}}\,(6.0)\,=2400\,\Omega \] Current in the primary coil  \[=\frac{240}{{{R}_{1}}}=\frac{240}{2400}=0.1A\]


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