useful for the b.tech. students

1. Prepared by:-
Sonu kumar bairwa

2.  Definition: -The obstruction offered by a
magnetic circuit to the magnetic flux is known
as reluctance.
 As in electric circuit, there is resistance similarly
in the magnetic circuit, there is a reluctance, but
resistance in an electrical circuit dissipates the
electric energy and the reluctance in magnetic
circuit stores the magnetic energy.
 Also in an electric circuit, the electric field
provides the least resistance path to the electric
current. Similarly, the magnetic field causes the
least reluctance path for the magnetic flux. It is
denoted by S.

5. The non-uniform magnetic circuit is made by adding the
uniform sections having the different value of a length,
cross-section area, and permeability of the magnetic
circuit.
 The reluctance of the non-uniform circuit is calculated
by adding the reluctance of the uniform section of the
magnetic circuit. The calculation of the non-uniform
magnetic field is more complex as compared to the
uniform magnetic field.
 In most of the transformer, an air gap is created for
reducing the effects of the saturation. The air gap
increases the reluctance of the circuit and hence stores
more magnetic energy before the saturation.

6.  Inductance is a key parameter in electrical
and electronic circuits. Like resistance and
capacitance it is a basic electrical
measurement that affects all circuits to some
degree.
 Inductance has variety of names: coils,
inductors, chokes, transformers etc.

7.  Inductance is the ability of an inductor to
store energy and it does this in the magnetic
field that is created by the flow of electrical
current.
 Energy is required to set up the magnetic
field and this energy needs to be released
when the field falls.
 s a result of the magnetic field associated
with the current flow, inductors generate an
opposing voltage proportional to the rate of
change in current in a circuit

8.  There are two ways in which inductance is
used:
 Self-inductance: Self-inductance is the
property of a circuit, often a coil, whereby a
change in current causes a change in voltage
in that circuit due to the magnetic effect of
caused by the current flow. It can be seen
that self-inductance applies to a single circuit
- in other words it is an inductance, typically
within a single coil. This effect is used in
single coils or chokes.

9.  Mutual-inductance: Mutual inductance is an
inductive effect where a change in current in
one circuit causes a change in voltage across
a second circuit as a result of a magnetic field
that links both circuits. This effect is used in
transformers.
 When indicating an inductor on a circuit
diagram or within an equation, generally the
symbol "L" is used. On circuit diagrams,
inductors are generally numbered, L1, L2, etc.
 The SI unit of inductance is the henery, H
which can be defined in terms of rate of
change of current and voltage.

10.  The inductance of a circuit is one henry if the
rate of change of current in a circuit is one
ampere per second and this results in an
electromotive force of one volt.
 One henry is equal to 1 Wb/A