Self-induction of a solenoid cannot be increased by
Self-induction of a solenoid cannot be increased by
decreasing its length
increasing its area of cross-section
increasing the current through it
increasing the number of turns in it
Solution
For a solinoid magnetic field at the center is:
$B=\mu_0\left(\frac{N}{l}\right) I$,
Total magnetic self flux is:
$\phi=B A N=\mu_0\left(\frac{N}{l}\right) I A N$
According to the definition of magnetic flux and coefficient of self induction:
$\phi=L I$
On comparing the above two expressions, the self-induction of a long solenoid is given by
$L=\frac{\mu_0 N^2}{L}$
where, $N=$ number of truns, $L=$ Length and $A=$ cross - sectional area.
Therefore, the self-induction of a long solenoid does not depend upon the current flowing through it.