Energy Conversion

Hello k.dhana

I have tried to understand what you are asking.

You say the electrons are already in the heating element = true.

You say the electrons are already in the connecting wires = true.

While the electrons are undisturbed ("not actually doing anything - passive"), the heating element will not give off (emit) any heat = true.

When the connecting wires are joined to a means of moving the electrons along the wires, it is the jostling and bumping of the electrons in the element wire which causes the heat = true.

Example:

People in a street, stationary, not moving. The people are just there, hardly moving, perhaps talking to each other.

People start moving because of some applied force = A large steamroller arriving down the street, and they must keep ahead of it.

Electrical similarity: People (electrons) run away from the steamroller (generator), but if they all arrive at a narrower part of the street, (high resistance), they crowd together, and energy is wasted (heat) by the jostling.

The analogy is not perfect, and I have tried to give one easily understood.

You ask where the energy actually comes from, and that is a valid question.

Using street people example: To move people in the street requires energy (steamroller fuel = coal), heating the water to steam, steam runs the boiler and thus energy transfers from the burned fuel (coal) to propel (move) the steamroller.

Thus it is with electricity.

Somewhere there is an energy source.

1. Sunlight energy gives Wind, Solar power, Hydroelectric, Coal, Wood, Oil, Chemical energy (plants)
   
2. Gravitational Energy plus Sunlight gives Tides, Wind, Hydroelectric.
3. Chemical Energy (from a cell or group of cells called a battery) gives electrical energy.
   

The Energy is transformed from one state to another, for assistance in moving that energy from where it is found, to where we want it to be used.

Example: Hydroelectricity to your heater element -

Sunlight causes evaporation of water, which falls as rain and snow in mountains, causing streams which join up to make rivers.

We dam the river, causing the water height difference (kinetic energy), allow the water to flow down through pipes (pen-stocks) through a turbine (propeller) at which point the kinetic energy in that falling water column is converted into mechanical energy which causes the turbine (propeller) to revolve.

Attached to the turbine shaft is an alternator, which converts the mechanical energy via magnetic fields to electrical energy in the conductors of the alternator.

The electrical energy is conducted along wires to a transformer, where the electrical energy is transformed into magnetic fields which vary, causing a different winding to be influenced by that varying magnetic field.

The electrical energy travels along wires to another transformer, where the electrical energy is transformed into magnetic fields which vary, causing a different winding to be influenced by that varying magnetic field.

the above may occur is several different steps, if your heater element is far away from the Power station.

There are losses at each energy conversion stage.

Important: The various % losses are multiplied, not added together.

So electrical energy arrives at your house, the to and fro of the alternating current is a reflection of the original alternator back at the Power station, where that water is pouring down the pen-stock, causing the turbine to revolve etc.

The higher resistance to electron movement (there are less free electrons in the heater element) causes the same equivalent to the narrower street and the steamroller coming towards them, the electrons get jostled by one another as they move, causing heat.

If the river stops flowing, the turbine stops rotating, and because the alternator does not now revolve, electrical power generation ceases, because there is no energy source, and far away at your home, the heater cools, the lights go out, and you have a "Power Cut".

In some respects the electrons in AC circuits never actually move from one place to another, but like a wave in the sea, where the wave moves but the individual water molecules stay where they were, just moving slightly in a tiny circle.

In DC (Direct Current) circuits, there is actual electron movement along the wire conductors, but the electron numbers are extremely large.

If you refer to: http://en.wikipedia.org/wiki/Electric_current

There you may read more about what the electrons do, where they go, depending on whether the electrical supply is AC or DC.

In all of this, it should be remembered that scientists do not really know what electricity really is, any more than light, gravity, magnetism and other physical properties are really understood.

Scientific theories have been made, observations taken, laws of physics are now established, because otherwise nothing may be even partly understood.

Every now and then, a new theory is made, and perhaps that theory is partly true, until a better one comes along.

I trust that I have not confused you with my reply.

Please advise if you have been helped, with

Kind Regards....