AMU Medical AMU Solved Paper-2007

  • question_answer
    A long solenoid has 20 turns /cm. The current necessary to produce a magnetic field of 20 mT inside the solenoid is approximately

    A)  1A                                         

    B)  2 A

    C)  4 A                                        

    D)  8 A

    Correct Answer: D

    Solution :

                     From the formula                 \[B={{\mu }_{0}}n\,I\] \[\Rightarrow \]               \[20\times {{10}^{-3}}=4\pi \times {{10}^{-7}}\times 2000\times I\] \[\therefore \]  \[I=\frac{20\times {{10}^{-3}}}{4\pi \times {{10}^{-7}}\times 2000}\] \[\Rightarrow \]               \[I\approx 8\,A\]


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