2. Sample Papers
  3. KVPY

KVPY Sample Paper KVPY Stream-SX Model Paper-9

  • question_answer
    A wire of fixed length is wound is such a way that it form a solenoid of length \['\ell '\] and radius 'r'. Its self inductance is fund to be L. Now if same wire is wound in such a way that it forms a solenoid of length \[\frac{\ell }{2}\] and radius \[\frac{r}{2},\] then the self inductance will be:

    A) 2 L

    B) L

    C) 4 L      

    D) 8 L

    Correct Answer: A

    Solution :

    \[L=\frac{{{\mu }_{0}}{{N}^{2}}\pi {{r}^{2}}}{\ell }\]
    length of wire \[=N\,\,2\pi r=\] Constant (= C, suppose)
    \[\therefore \]      \[L={{\mu }_{0}}\,\,{{\left( \frac{C}{2\pi r} \right)}^{2}}\frac{\pi {{r}^{2}}}{\ell }\]
    \[\therefore \]      \[L\propto \frac{1}{\ell }\]
    \[\therefore \]      Self inductance will become 2L.


You need to login to perform this action.
You will be redirected in 3 sec spinner