Learn more physics!
from your understanding or research of electromagnetic induction, can u explain why transformers can be used in AC power systems and not DC power systems for power distrubution
That's a really good question.
For a transformer to work, the current in one coil has to somehow
make current flow in the other coil and the circuit it's connected to.
A DC current in one coil will make a magnetic field on the other coil,
but a magnetic field by itself won't drive any electrons around. A
CHANGING magnetic field, however, does create an electric force which
will accelerate those electrons in the other coil into carrying a
current. This process is described by Faraday's law of induction. You
get a changing field from an AC current, since the current which makes
the field is changing.
(republished on 08/02/06)
Follow-Up #1: transformers
YOU EXPLAINED THAT TRANSFORMERS CANíT WORK ON DC BUT I WOULD LIKE TO KNOW THAT WHAT ID THE EXACT EFFECT OF A TIME VARYING FIELD AND ONE MORE THING IN HVDC TRANSMISSION TRANSFORMERS ARE BEING USED, WHAT IS THAT?
- MAYANK (age 22)
BANGLORE, KARNATAKA, INDIA
The effect of time-varying magnet fields is to produce an electromotive force (EMF) driving charged particles around. The effect is described exactly by Maxwell's equations. The current in the primary of the transformer produces a magnetic field. When the current changes, so does the field. That makes an EMF which drives current in the secondary.
I'm guessing that in the application you describe some dc current is chopped into an ac current (maybe by switching some contacts back and forth) and the ac current is then run through a transformer. It could then be converted back to dc by a rectifier.
(published on 04/07/07)
Follow-up on this answer.