3. Introduction
Building block of electrical/electronic circuits which stores energy is the
linear passive element called capacitor.
The unit of capacitance is Farad(F)
Some general prefixes related to capacitors are milli,micro and pico Farad.
The general symbol of capacitor is :-
4. Properties
The charge accumulated on capacitor is given by :-
Q=CV
‘C’ is not dependent on ‘q’ or ‘v’ but on the physical dimensions of
capacitor.
Where ε= permittivity of material
5. Capacitor current is given by :-
Hence it acts as open circuit to DC because dv=0.
Capacitor resists change in voltage abruptly because dt = 0 would
mean infinite current.
10. Introduction
An inductor is a coil of wire having magnetic properties.
Is a passive two terminal electric component which resists
changes in electric current passing through it.
It consists of a conductor such as a wire, usually wound into a
coil. When a current flows through it, energy is stored
temporarily in a magnetic field in the coil.
Whenever current passes through a conductor, lines of
magnetic flux are generated around it. This magnetic flux
opposes any change in current due to the induced e.m.f.
This opposition to the current is known as inductance and the
component producing inductance is known as inductor.
11. Relationship
Induced e.m.f (Electromotive force)
Unit is Henry(H)
The inductance of a coil is one henry if a current changing at the rate
of 1 ampere/sec creates a voltage of 1 volt.
Depends upon no of turns, permeability(µo), core size.
Permeability is the measure of the ability of a material to support the
formation of a magnetic field within itself. (4π X 10E-7) H/m
12. Ideal and non ideal behaviour
An "ideal inductor" has inductance, but no resistance or capacitance, and
does not dissipate or radiate energy.
However real inductors have resistance and parasitic capacitance (due to
the electric field between the turns of wire which are at slightly different
potentials).
At high frequencies the capacitance begins to affect the inductor's behaviour.
Inductors with ferromagnetic cores have additional energy losses due
to hysteresis and eddy currents in the core
At high currents, iron core inductors also show gradual departure from ideal
behaviour due to nonlinearity caused by magnetic saturation of the core.
An inductor may radiate electromagnetic energy into surrounding space and
circuits, and may absorb electromagnetic emissions from other circuits.
15. Applications
Transformers
switched-mode power supplies to produce DC current
particularly in radio equipment.
They are used to block the flow of AC current while allowing DC to pass;
inductors designed for this purpose are called chokes.
They are also used in electronic filters to separate signals of different
frequencies, and in combination with capacitors to make tuned circuits, used
to tune radio and TV receivers.
