i have some questions regarding inductor as it need in design. till now i don't have used inductor bcoz of his behaviour.
as written inductor allows steady current flowing through it that is DC?
how much current it can pass example 680uH?
and inductor oppose to flow AC?

 

An inductor opposes a change in current flow, by storing and releasing energy from a magnetic field created by the inductor. So it can be said to oppose AC but not DC.

The ability to pass DC depends on the DC resistance, which does not have to be directly related to the inductance. So the DC current max cannot be predicted from the µH rating alone.

 

the dc current is determined by the size of the wire.

 

And the ∆V, the length, the composition, and the temperature.

 

You might want to review my video on the voltage and current relationships in capacitors and inductors...
http://www.youtube.com/watch?v=ykgmKOVkyW0

 

Two conditions
if current is more than inductor rating? in DC condition.

 

lol The old timers read txt speak better than I do! I had to read it 4 times

 

where is use of RLC circuits.
means appliaction??

 

All real components have R, L and C values. Are you asking where inductors are used? Oscillators, such as in radio transmitters, is one of many common places to find an inductor.

 

Common uses for inductors are energy storage (in switching power supplies), power supply filtering, signal filtering, oscillators...