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NEET Sample Paper NEET Sample Test Paper-38

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

    A)  90V        

    B)  120V

    C)  220V       

    D)  30V

    Correct Answer: B

    Solution :

     The magnetic flux linked with the primary coil is given by \[\phi ={{\phi }_{0}}+4t\] So, voltage across primary \[{{V}_{p}}=\frac{d\phi }{dt}=\frac{d}{dt}({{\phi }_{0}}+4t)=4\,volt\](as \[{{\phi }_{0}}=\text{cosntant}\]) 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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