Test: Types of Inductor & Inductance - Electrical Engineering (EE) MCQ

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 average emf induced in a coil= L=NΦ/t.

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

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

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.

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

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 two types of inductors are fixed and variable inductors. Fixed inductors are those whose inductance value cannot be changed. Variable inductors are those whose values can be changed as and when required.

 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.

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.