Electromagnetic Induction Ques 29

29. If the number of turns per unit length of a coil of solenoid is doubled, the self-inductance of the solenoid will

(a) remain unchanged

(b) be halved

(c) be doubled

(d) become four times

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Answer:

Correct Answer: 29.(d)

Solution:

  1. (d) Self inductance of a solenoid $=\frac{\mu n^{2} A}{\ell}$

So, self induction $\propto n^{2}$

So, inductance becomes $4$ times when $n$ is doubled.