Inductor 6v1g3y

INDUCTORS  Moving current in a conductor can produce magnetic field

 Electrons in motion have an associated magnetic field

 Moving magnetic field produces an electric field

 Such effects are called as electromagnetic effects

 Electromagnetic effects found in electronic components such as  Inductors  Transformers

INDUCTOR Inductor (coil) is an electromagnetic device consisting of a conductor wound in cylindrical or spiral form to obtain concentrated field parallel to the axis of the coil

L Symbol Indicated by the letter ‘L’

SPIRAL FORM

Units : Henry

PROPERTY OF INDUCTOR INDUCTANCE (OR) SELF-INDUCTANCE It is defined as the ability of a coil to induce an e.m.f in itself due to change in current (or) Ability of an inductor which opposes the change in current (or) Ability of a conductor to induce voltage in itself when the current changes

INDUCED VOLTAGE

The self induced voltage ‘VL’ across an inductor is given by VL = - L.di / dt VL = induced voltage in volts L = inductance in Henrys di / dt = rate of change of current in amperes per second • Minus sign indicates the polarity of induced voltage which opposes the change in current

MUTUAL INDUCTANCE It is the ability of varying current in one inductor (L1) induce voltage in another inductor (L2) near by

Mathematically expressed as LM = K SQRT(L1L2) where ‘K’ is co-efficient of coupling between two inductors ‘K’ is defined as degree of magnetic coupling

FACTORS AFFECTING THE INDUCTANCE OF AN INDUCTOR l

Length of a coil

Area of cross-section of a coil

A N

Number of turns

L = µr (( N2.A ) / l ) x 1.2 x 10-6 H where µr is the relative permeability L – Length in mts N – Number of turns A – Area of cross section in m2

TYPES OF INDUCTORS According to core material

Air core Ceramic core Plastic core

Non-magnetic core materials

Glass core

Cobalt Nickel alloy Iron core

Magnetic materials

AIR CORE INDUCTOR

IRON CORE INDUCTOR

According to operating frequency

Audio frequency inductors

Radio frequency inductors

At these frequencies iron

At these frequencies air

core inductors are used

core inductors are used

Inductance varies from 1

Inductance varies from

to 25Henries

milli Henries Henries

to micro

According to method of winding

Single layer Multi layer Honey comb Pi - section Universal winding Single layer and universal windings are mostly used

SYMBOLS

AIR CORE INDUCTOR

VARIABLE INDUCTOR

IRON CORE INDUCTOR FERRITE CORE INDUCTOR

VARIABLE IRON CORE INDUCTOR

TRIMMER INDUCTOR

VARIABLE FERRITE CORE INDUCTOR

DIFFERENT INDUCTORS

APPLICATIONS In analog circuits and signal processing Inductors in conjunction with capacitors and other components form tuned circuits which can emphasize or filter out specific signal frequencies. Smaller inductor/capacitor combinations provide tuned circuits used in radio reception and broadcasting, for instance. An inductor is used as the energy storage device in some switched-mode power supplies Inductors are also employed in electrical transmission systems, where they are used to depress voltages from lightning strikes and to limit switching currents and fault current

INDUCTORS ON BOARD