CMC Medical CMC-Medical VELLORE Solved Paper-2008

  • question_answer
    If a current of 500 mA produces a deflection of \[30{}^\circ \] in a tangent galvanometer, then the current that produces a deflection of \[60{}^\circ \]is

    A)  1.5 A                    

    B)  1 A

    C)  500 mA               

    D)  866 mA

    E)  2A

    Correct Answer: A

    Solution :

                    If an electric current \[I\] is flowing through the coil of the tangent galvanometer and the magnetic needdle gets deflected and comes to rest making an angle \[\theta \] with the direction of horizontal component of earths magnetic field H, then for the tangent galvanometer \[I=K\tan \theta \] where K is the reduction factor of tangent galvanometer. \[\therefore \]  \[\frac{{{I}_{1}}}{{{I}_{2}}}=\frac{\tan {{\theta }_{1}}}{\tan {{\theta }_{2}}}\] or            \[\frac{500}{{{I}_{2}}}=\frac{\tan 30{}^\circ }{\tan 60{}^\circ }\] or            \[\frac{500}{{{I}_{2}}}=\frac{\left( \frac{1}{\sqrt{3}} \right)}{\sqrt{3}}\] or            \[\frac{500}{{{I}_{2}}}=\frac{1}{3}\] or            \[{{I}_{2}}=1500\,mA=1.5A\]


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