why inductor resist changes in current??

hi

my elementary doubt is how inductor oppose changes in current

eg

if i connect 10v battery to an inductor.


assume inductor has no energy stored

voltage across inductor is 0v,
at t= 0 --

current thru the inductor is 0
resistance is 1ohm.

if i connect 10v battery to inductor at t=0

i = 10V/1 =10A.

IS this inrush current??
exact definition of inrush current ??

wen a sudden 0 to 10A current flow thru an inductor, by electromagnetisim , a change in magnetic field around the inductor will be created,

is this change in magnetic field. cauce force on the inductor ?

(when a current carying conductor in a magnetic field experience force )

is this force is the reason for the inductor oppose to changes current.

or by faradys law
changes in magnetic field produce an emf induced in the conductor by LENZs Law the direction of induced emf is which oppose the cauce.

that means induced emf produce a current ,this current will produce another magnetic field ,

this magnetic field should oppose the main magnetic field, so the current direction is opposite to the applied current

if applied current is ( 0 to 5A) , AT SAME TIME , is inductor oppose a current ( 0 to -5A),??

IF THE SELF INDUCED EMF IS 180 DEG PHASE SHIFT OR equal and opposite,

induced emf is -10V,

then applied voltage and induced emf cancel each other,
no current, no magnetic field,

really i try to visualize this small inductor , its principle, by eqn and mathematically its ok.

pls help me ,whats the true working principle from deep basic on electromagnetisim..

also point out my misconcept.


regards

mobin

Re: how inductor oppose changes in current

At t=0 current from battery starts to flow and hence charges the inductor.
A current through a conductor produces a magnetic field around it as per Biot-Savart's law. That magnetic field induces an emf around the inductor as per Faraday-Lenz's law. That emf is in such way that opposes the cause which produces it and hence the inductor opposes change in current.

mobinmk said:

if i connect 10v battery to inductor at t=0

i = 10V/1 =10A.

IS this inrush current??

Click to expand...

No current flows at t=0 or immediately after that.

10A is what we could call a 'target' figure. Current eventually builds to that level.

As current builds, counter-EMF drops.

BradtheRad said:

As current builds, counter-EMF drops.

Click to expand...

THANKS bradthe rad,

now my doubt is as current builds

how counter emf drops ??

- - - Updated - - -

CataM said:

At t=0 current from battery starts to flow and hence charges the inductor.
A current through a conductor produces a magnetic field around it as per Biot-Savart's law. That magnetic field induces an emf around the inductor as per Faraday-Lenz's law. That emf is in such way that opposes the cause which produces it and hence the inductor opposes change in current.

Click to expand...

Thnkz CataM

OnLy changes in magnetic field induce an emf across inductor.
which will equal and opposite to applied voltage

thus current produced by induced emf oppose the current by applied voltage.

then no voltage. no field

no current flow thru inductor

OnLy changes in magnetic field induce an emf across inductor.
which will equal and opposite to applied voltage

Click to expand...

Yes if we are talking in the ideal case i.e. a mesh with ideal voltage source and ideal inductor.

thus current produced by induced emf oppose the current by applied voltage.

then no voltage. no field

no current flow thru inductor

Click to expand...

There will be a current that oppose the applied voltage but smaller than the current from the soruce BUT this does not mean that the induced emf (counter emf) is different than the voltage source.

In your case, if you apply 10V DC to an ideal inductor, the counter emf=10 V and the current through it will raise to infinity i.e. will discharge the source very fast.