VIT Engineering VIT Engineering Solved Paper-2015

  • question_answer
    The value of inductance L for which the current is maximum in series LCR circuit with \[C=10\mu F\] and (0=1000 rad/s

    A) 10 mH                                  

    B)  50 mH

    C) 200 mH                

    D)  100 mH     

    Correct Answer: D

    Solution :

    In resonance condition, maximum current flows in the circuit.                 Current in the LCR circuit is given by                                                                   \[\therefore \]                 For current to be maximum denominator should be minimum                                      \[{{E}_{R}}=\frac{\sqrt{3}q}{4\pi {{\varepsilon }_{0}}{{r}^{2}}}\]                 \[\tau =qEL\sin \theta \]          \[=qEL\theta \]                 \[\because \]          \[\theta \]                 \[\text{I=m}{{\left( \frac{\text{L}}{\text{2}} \right)}^{\text{2}}}\text{+m}{{\left( \frac{\text{L}}{\text{2}} \right)}^{\text{2}}}\text{=}\frac{\text{m}{{\text{L}}^{\text{2}}}}{\text{2}}\]            \[\tau =I\alpha \]                           \[\text{ }\!\!\alpha\!\!\text{ =}\frac{\text{ }\!\!\tau\!\!\text{ }}{\text{I}}\text{=}\frac{\text{qEL }\!\!\theta\!\!\text{ }}{\frac{\text{m}{{\text{L}}^{\text{2}}}}{\text{2}}}\]                                             \[\Rightarrow \]                           \[{{\text{ }\!\!\omega\!\!\text{ }}^{\text{2}}}\text{ }\!\!\theta\!\!\text{ =}\frac{\text{2qEL }\!\!\theta\!\!\text{ }}{\text{m}{{\text{L}}^{\text{2}}}}\]  L = 0.1 H = 100 mH       


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