JCECE Medical JCECE Medical Solved Paper-2011

  • question_answer
    The \[80\,\Omega \] galvanometer, deflects full scale for a potentials of 20 mV. A voltmeter deflecting full scale of 5V is to made using this galvanometer. We must connect

    A)  a resistance of \[19.92\,k\Omega \]parallel to the galvanometer

    B) a resistance of \[19.92\,k\Omega \]in series with the  galvanoyneter

    C)  a resistance of \[20\,k\Omega \]parallel to the galvanometer

    D) a resistance of \[20\,k\Omega \]in series with galvanometer

    Correct Answer: B

    Solution :

     The current through galvanometer producing full scale deflection is \[I=\frac{V}{R}=\frac{20\times {{10}^{-3}}}{80}\] \[=2.5\times {{10}^{-4}}A\] To convert galvanometer into. a voltmeter, a high resistance is connected in series with the galvanbmeter                  \[5=(2.5\times {{10}^{-4}})(R+80)\] \[R=19.92\,k\Omega \]


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