> Thank you all for your answers but I find them, somehow, canned
> information provided by the brain washing dogma that today universities
> call learning
I will try to add my two cents, maybe it will help, maybe not. Some of what
we learn in school is indeed meant to be taken for granted, because there
are concepts that our human brains have difficulty understanding. We
understand best what we can see, and many things can't be seen.
> Take for example the "electromagnetic field" Evidently, this has to do
> something with electrons as the abbreviation "Electro" is part of it
Actually, no. At least, not necessarily. I think this is an unfortunate
consequence of how our understanding of electricity and magnetics evolved
over a couple of centuries. "Electromagnetic fields" and "electrons" do
both have something to do with electricity, and I think that's how they got
the "electro" in their names. But not one from the other.
An electric field is similar to an invisible force that can exist in air,
even in a vacuum. It is odorless, colorless, etc. etc. It might involve
electrons in the matter that surrounds or interacts with that field, but it
might not. (Actually, it probably always does "involve" electrons, because
electrons are part of all matter, either by their existence or by their
absence.)
But the field itself does not consist of electrons, or any other matter.
The field might cross through some matter, but it can just as easily be in a
total vacuum.
It is similar to gravity, which is a field or a force that exists between
any two big objects, but which does not require or use any matter in the
space between the objects.
Gravity and electromagnetic forces are two of the four primary forces in our
understanding of the universe. The other two only make themselves known at
the atomic or sub-atomic level so we don't talk about them much.
These are somewhat difficult concepts to wrap our brains around because we
can't actually see and feel them (well, we do feel gravity), and it seems
like magic, so very often we need to take them for granted.
Imagine two pieces of metal, maybe two plates, separated by some space, and
connected to a very large battery. Let's say a million volt battery. For
the heck of it, also connect one of the plates to ground. Now stick an
object in the space between the two, with a voltmeter probe on it so you can
measure its voltage (relative to ground). When this object is in contact
with the grounded plate, obviously the voltage is ground, or zero. When it
touches the other plate, the voltmeter shows it has a million volts on it.
But what about when it's touching neither plate? One might say, there isn't
any voltage on it now; how could there be? But actually, you will see a
voltage on it, depending on where it is between the two plates. The voltage
on it will be seen to vary in relation to how far it is between the two
plates.
What makes this happen, is the electric field between the plates. The
charges on one plate, and the opposite charges on the other plate, cause
this "electric field" in the space between the plates, stretching from one
plate to the other.
In actuality, every electron and every proton has an electric field around
it. (Neutrons don't, because they have neutral charge.) Most of these
small electric fields cancel out, because there are as many electrons as
protons. But when you charge up some piece of mass, you cause more
electrons than protons, or vice-versa, and then you are left with a net
electric field in the area around the mass.
It's not easy to explain the field in more concrete terms. There could be
no electrons in the space between the plates where the electric field is.
In a sense, the "electric field" is the concept we use to explain the fact
that the object between the plates will get a voltage on it, even though
it's not touching anything. The field is very real; just not something that
fits how we interacted with our toys when we were growing up and learning
how the world worked. It is a seemingly-magical thing that transcends solid
objects.
As you know, you can also have magnetic fields, say around a bar or
horseshoe magnet. These fields are also invisible, odorless, etc., and seem
like magic because no matter is actually involved, yet they can somehow make
objects move.
What I described was a static (unchanging) electric field.
Now, when you start varying an electric field (say by connecting those
plates to an AC voltage source), what happens is that it also causes a
varying magnetic field at the same time, and the two of them vary together
in an intricate way. We call this an "electromagnetic field," because it
includes the interrelated electric and magnetic components and you can't
have one without the other.
> So, if the antenna generated an Eletrofield, is it composed of electrons?
The field is not. However, the thing that caused the field to exist,
probably has electrons. The antenna has electrons moving in it, along the
metal, back and forth.
> If so, where are they coming from? If they are originating somewhere in
> the transmission equipment, by ejecting them through the antenna is the
> transmitting equipment loosing mass?
A simplistic view is that the electrons are coming from the transmitter and
go out the feedline to the antenna, and back and forth. In reality,
electrons only jump from atom to nearby atom, and the ones that come from
the transmitter might not make it all the way to the antenna. Instead, they
go to an atom, giving it a negative charge, which then gives up one of its
electrons (maybe the same one, maybe not) which jumps to the next atom, and
so on. But you don't need to worry about all that.
> There is no pure energy. All energy must have a mass substrate. Otherwise
> it should travel at speeds greater than light. This is well documented by
> Einstein.
I hate to say it, but there is much that is wrong with your statement.
Energy is not mass. Energy is energy, and yes, there is pure energy.
Energy can be converted into mass, and vice-versa, as documented by
Einstein. Light is pure energy and travels at the speed of light. Light
is, in fact, an electromagnetic field, just like all the other
electromagnetic fields we've been talking about. What makes light special
is that it is in a very specific frequency range, that's all. Too low a
frequency, and we can't see it; too high, and we can't see it either.
If light were mass, or required a mass substrate, it could not travel
through a vacuum. But it does. Just as radio waves do.
> Take for example a transmitting tube. Its katode has a specific live span
> after which it can not emit any electrons. Where have all its electrons
> gone? Did the tube loose mass?
I think you don't understand very well how tubes work. The cathode emits
electrons into the space above it, and those electrons are constantly being
refreshed by the wire connected to the cathode and the external circuit. If
you disconnect that wire, no more electrons get to the cathode and it stops
working in a nanosecond.
The life span of a tube is because the cathode is constantly being stressed
(also burning off other atoms in addition to its electrons), and eventually
it loses the ability to throw off excited electrons as well. By the time it
has worn out, the cathode will have emitted a trillion times the number of
electrons that it initially had, yet it has not lost any electrons because
it got all of them from the rest of the circuit. Once it's dead, you can
pour more electrons onto it but it won't help much; it just can't "boil them
off" very well anymore.
> A simple example will be a dynamo and bulb connected to it.. By turnig the
> dynamo we are generating electricity (read electrons) that enter the bulb.
> Some of them are spent in creating photons (light) some of them create
> heat and some of them are simply lost in the never never land. And here
> comes the same question. Where are these electrons/mass come from? From
> the cooper in the coil? Why do we not detect mass loss of the coil after
> some period of time?
Well, you can't create electrons. Not easily, at least.
The dynamo doesn't create any electrons, it just moves the electrons that
are already there. Those electrons that create heat don't cease to exist
either; they just lose energy and move slower, but they still exist.
The electrons that enter the bulb also leave the bulb on the other wire.
Along the way, they give up some of their energy; but they still exist as
electrons. None of them are spent or lost.
Electricity consists of MOVING electrons. It is the fact that they are
moving, that gives us energy from electricity. All those electrons keep on
existing; and anytime you have electricity moving through a wire, you have
to keep feeding it new electrons on one end, while taking them out of the
other end. Hence, the mass of a coil does not change over time. (Well yes,
a wire or coil with a positive static charge would weigh very slightly less
than one with neutral or a negative charge.)
Hope this helps.
Andy
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