Electromagnetic Induction - Result Question 31

31. If $N$ is the number of turns in a coil, the value of self inductance varies as

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(a) $N^{0}$

(b) $N$

(c) $N^{2}$

(d) $N^{-2}$

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Answer:

Correct Answer: 31. (c)

Solution:

  1. (c) $L=\frac{N \phi}{i} ; \phi=B A ; B=\frac{\mu_0 N i}{2 R}$

$\Rightarrow L=\frac{N}{i}(\frac{\mu_0 N i}{2 R}) A=\frac{\mu_0 N^{2}}{2 R} A \Rightarrow L \propto N^{2}$