# How transformers actually operate

1. Jan 11, 2005

### sp00ky

I was just wondering how transformers actually operates. And I hear they need to use alternating current and I was just wondering why they need to do so.

2. Jan 11, 2005

### The Bob

Transformers are large, ringed, pieces of metal that have two sets of coils around opposite sides. An AC current is used because this induces a magnetic field, that a DC does not. A different in the number of coils in the different sets means that the voltage changes from low to high or high to low (high and low not set values).

Last edited: Jan 11, 2005
3. Jan 11, 2005

### chroot

Staff Emeritus
To clarify Bob's post a little:

Transformers require AC because passing AC through a coil creates a changing magnetic field around that coil. DC certainly does produce magnetic field, but it does not change with time.

When an AC current is passed through one of the transformer's two coils (usually called the primary winding), its changing magnetic field also engulfs the other coil (usually called the secondary winding). The electrons in the secondary winding react to the changing magnetic field by continuously moving. (If you applied a DC current instead, the electrons in the secondary winding would only move for a split second, then settle down -- you'd get no continuous current.)

In other words: a changing current in the primary winding induces a changing current in the secondary winding.

Transformers thus allow the movement of electrical energy from one wire to another, without the wires ever having to touch -- the energy moves from one wire to the other through the changing magnetic field. As The Bob says, the ratio of the number of turns on one coil to the other also determines the ratio of the potential differences (voltages) through the two coils.

- Warren

4. Jan 11, 2005

### sp00ky

okay...and is there only 2 types of transformers? A step up and a step down is basically the types of transformers there are right?

5. Jan 11, 2005

### The Bob

I can't see there being any others. You can step up the potential difference and step down the potential difference but what is the point in havong a transformer to keep the potential difference the same???

Chroot might say different and he will, therefore, be right but I think there can only be two.

6. Jan 11, 2005

### sp00ky

I know step-up transformers are used for tv's, pc monitors, and in many furnace-ignition circuits, but what types of stuff are used for step-down? I know some toys does but anythn' else?

7. Jan 11, 2005

### vincentchan

In order to minimize the energy loss, the transmition line from the power plant and you house operates at a very high voltage, Over 100kV is not uncommon.... but your power outlet is 110V only.... how do they do that? and why are they using A.C. (alternating current)?

8. Jan 12, 2005

### Zaimeen

Added to vincentchan notes, what component is integrated in your charger when you want to charge your mobile phone sp00ky?