Let's draw an analogy between household gas and electric current.

Earlier I compared current with gasoline. In fact, everything is the same. I believe that the electric current, as well as gasoline (oil), natural gas, coal! water! etc, is fuel. Fuel of natural origin, which does not require extraction and processing. This type of fuel is in any conductive material (conductor). We will not talk about electrons and their charges. Just try to accept it as a kind of fuel, locked inside the conductor, as well as the gas in the tank.

The gas itself does not carry any energy, but you just need to give a spark and it will ignite and burn, but only if there is a constant presence of oxygen. The more we open the cylinder valve, the more gas will burn and the more energy will be released in the form of heat (and in a closed container, pressure). If the ignition occurs in closed container, then for certain amount of gas certain amount of oxygen will be required.

Practically the same process with the electric power.

Container with "gas" is conductor, voltage is "oxygen", and the connected load is valve that regulates "gas" supply (passage). There is a lot of fuel in the conductor, and what amount will "burn" depends on the voltage (the amount of oxygen supplied) and the load (valve). The circuit closing is a "spark for ignition". Gas in the tank is not infinite, and the conductor is also depleted and eventually sticks.

Now let's move to the work of our current ("gas").

Understanding of an ordinary person - we get current from the source, such as household electricity (talking about conventional household devices). We plug the lamp cord into the socket, the current goes and the lamp lights up. Now to understand what is really going on, we need to put a transformer between the lamp and the socket. Many will say what does it have to do with the transformer. In fact we are all connected through the transformer, in any household there is a transformer box, and from it there are "extensions" to the switchboard and then to the apartments. It is all the same in private houses and everywhere in general. Transformers in booths are connected to other more powerful ones, etc. to the electro-generation station itself. We put our transformer, so that everything would be clearer and more understandable. The transformer completely unleashes the load from the source, that is, our load is not physically connected to the previous source. There is primary coil connected to the source, in our case to the socket and secondary coil to which our light bulb is connected. These two coils do not have any electrical connection, they are isolated from each other. The voltage ("oxygen") applied to the primary coil, which is closed (a spark for ignition), creates current in it (gas combustion), the valve is the coil itself (it has its inductance and resistance both reactive and active). This current in its turn generates magnetic field. This magnetic field induces EMF (voltage) on the secondary coil. Here pay attention - the magnetic field induces EMF, appears voltage ("oxygen") on the secondary coil, but there is no current (combustion of the gas does not occur, but conditions are created). Turning on the light bulb, the circuit closes and current begins to flow (ignition and combustion occur). The current is created by the load, it did not come from the primary winding and was not transmitted by the magnetic field. Depending on the induction of magnetic field, the voltage on the secondary coil of our transformer and its power will depend. To create a powerful induction, no large current consumption is required. Ordinary transformer requires 10-15% of the power from its nominal to create magnetic induction 1-1.5 Tesla. For you to understand what 1 Tesla is - Medical device MRT has magnetic field from 0.8 to 1.5 Tesla.

So why does the current consumption by the primary coil of the transformer increase?

As I said above, the winding of the transformer has its inductance and accordingly reactance (not be confused we will say just resistance). This resistance depends on inductance and frequency of the current (we have 50Hz). Connecting the load to the secondary coil of the transformer the current, which also creates magnetic field, starts to flow, but opposite to the direction of magnetic flux of the primary. Because of this, the inductance of the primary decreases and accordingly the resistance decreases, which leads to increasing of current consumption. Although this power (this current) is not used to maintain the glowing of the light bulb, but only strengthens primary magnetic field. As a result, the total acting magnetic field will always be equal to the magnetic field created by blank run current, that is, no matter, whether we have light bulb connected or not. In fact, we spend most part of energy from the source, due to decreasing in inductance, not because of the load demand.

My transformer is made in such a way that effect of the magnetic flux created by the load decreases significantly and may even not function at all. The system is very simple, but at the same time, there are some subtleties and dependencies between field interference. Decreasing influence - we lose tension. However, it all can be solved 

Why did I draw parallel between gas and current? As everyone understands, energy is not taken from somewhere, the law of energy preservation has not yet been canceled. Then where does the current flow from to the load if it does not come from the source? The conductor contains a natural element (electron), which under certain conditions (voltage and closure through the load) releases energy.

Maxsus Kudratov