i want to understand few things about adapter...
voltage is stepped down in transformer, what is the current in primary coil how current is compensated in both coils let say we stepped down from 110v to 30v.?
how filtration helps in getting dc?
what does current ratings on adapter mean?

 

Welcome to AAC!

Most wall warts are simple DC power supplies, though they can vary a lot.

Submission: Power Supply Circuits

 

sorry but i cudn't understand wat u r tryin to say...i m new here :/

 

Wall Wart.........technical slang for the power supplies one plugs into household AC to provide proper reduced DC voltage for a - radio -- tape player etc.

current potential in both coils when plugged in, is the same as the source it is plugged into. Shorts can fry them instantly, or cause unacceptable heating.

Magnetic coupling of the two different coils transfers the voltage & current. Turns ratio of the coils, dictates output voltage.
Size of wire in the coils, dictates a limit to potential, or how much current is available for a device to draw

Filtration is necessary -- have you ever heard an annoying hum in any sound system speakers ? there are a truckload of possible filtration circuits.

Sounds as though you need to check into the site textbooks, and spend some time reading........starting with basics.