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NEET Sample Paper NEET Sample Test Paper-70

  • question_answer
    The primary and secondary coils of a transformer have 50 and 1500 turns respectively. If the magnetic flux \[\phi \] linked with the primary coil is given by \[\phi  ={{\phi }_{0}} +4t\], where \[\phi \] is in weber, t is time in second and \[{{\phi }_{0}}\] is a constant, the output voltage across the secondary coil is

    A) 90 V                

    B) 120 V

    C) 220 V              

    D) 30 V

    Correct Answer: B

    Solution :

    The magnetic flux linked with the primary coil is given by \[\phi ={{\phi }_{0}}+4t\] So, voltage across primary \[{{V}_{p}}=\,\frac{d\phi }{dt}=\frac{d}{dt}({{\phi }_{0}}+4t)\] \[= 4 V \left( as {{\phi }_{0}} = constant \right)\] Also, we have \[{{N}_{p}}=\,\,50\,\,and\,\,{{N}_{s}}=1500\] From relation. \[\frac{{{V}_{s}}}{{{V}_{p}}}=\frac{{{N}_{s}}}{{{N}_{p}}}\] \[or\,\,\,\,\,\,{{V}_{s}}={{V}_{p}}\frac{{{N}_{s}}}{{{N}_{p}}}=4\left( \frac{1500}{50} \right)\] \[=\,\,\,120\,V\]


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