Factors Determining The Inductance Of A Coil - GATE EE Basic Electrical

Inductance is directly proportional to the square of the number of turns in the coil, hence as the number of turns increases, inductance also increases.

Inductance is directly proportional to the magnetic field strength in the coil, hence as the magnetic field strength increases, inductance decreases.

The formula for magnetic field strength in a coil is:
H=iN/l
The inductance is: directly proportional to magnetic field strength, hence as the current value doubles, the inductance also doubles.

 When a coil is wrapped around a ferromagnetic core, it is difficult to determine the inductance because the variation of flux is no longer proportional to the variation of current.

The formula for inductance is:
L=4*pi*10^-7*A*N²/l, hence as the area of cross section A increases, the inductance also increases.

The formula for inductance is:
L=4*pi*10^-7*A*N²/l, hence as the length of the magnetic circuit l increases, the inductance decreases.

The average emf induced is proportional to the current per unit time, the constant of proportionality being L. Hence emf=LI/t. Making L the subject of the formula, we get: L=emf*t/I.

The unit of induction is named after a famous scientist Joseph Henry who independently discovered electromagnetic induction.

For a coil having a magnetic circuit of constant reluctance, the flux is directly proportional to the current.

Inductive reactance is nothing but the impedance. Impedance is the AC equivalent of resistance, hence the unit for inductive reactance is ohm.