Question

A coil of $100$ turns with a current of $5\text{A}$ produced a magnetic flux of $1\mu \text{Wb}$ at each turn of the coil. The coefficient of self induction is-

• A. $40\mu \text{H}$
• B. $30\mu \text{H}$
• C. $20\mu \text{H}$
• D. $10\mu \text{H}$

Answer 1

The correct option is C $20\mu \text{H}$

Given, $N=100;\varphi =1\mu \text{Wb};i=5\text{A}$

As we know,

$N\varphi \propto i$

$N\varphi =Li$

<!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> Hence, $\left(C\right)$ is the correct answer.

$100\times 1\times {10}^{-6}=L\times 5$

$L=2\times {10}^{-5}\text{H}$

$=20\times {10}^{-6}\text{H}\text{(or)}$

$L=20\mu \text{H}$