EAMCET Medical EAMCET Medical Solved Paper-1998

  • question_answer
    A galvanometer has coil of resistance 50 \[\Omega \] and shows full defection at 100\[\mu \]A. The resistance to be added for the galvanometer to work as an ammeter of range 10 in A is:

    A)  0.5 \[\Omega \] in series            

    B)  0.5 \[\Omega \] in parallel

    C)  50 \[\Omega \] in series              

    D)  50 \[\Omega \] in parallel

    Correct Answer: B

    Solution :

                     Here: Resistance of galvanometer \[G=50\Omega \] Current through galvanometer \[{{i}_{g}}=100\mu A\] \[=100\times {{10}^{-6}}={{10}^{-4}}A\] \[i=10\,mA=10\times {{10}^{-3}}=100\times {{10}^{-4}}A\] Shunt required is \[S=\left( \frac{{{i}_{g}}}{i-{{i}_{g}}} \right)G\] \[S=\frac{{{10}^{-4}}}{(100\times {{10}^{-4}}-{{10}^{4}})}\times 50=\frac{{{10}^{-4}}\times 50}{99\times {{10}^{-4}}}\] \[\approx 0.5\,\Omega \] The shunt resistance is connected in parallel to convert galvanometer into ammeter.


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