Basic Electricity and Magnetism For Astronomers
An explanation of what electricity
and magnetism are really like in practice.
Note that most of what is written here can be checked by the reader.
This essay has been produced because too many authors have repeated
what others have written without checking the facts for themselves.
1. The Basic Basics
Electricity is something we take for granted today. It comes in
two sorts. The most used sort comes from wall so
ckets.
(I will explain how it gets to wall sockets later.)
The other sort comes from batteries. The purists call one unit
of a battery - a cell. I'm a purist. The first image shows four
popular cylindrical cell types.
Cells come in may varieties. The most commonly used cell these
days is the AA size. The next most common is the AAA size which
is smaller. There are larger C and D size cells but these are
not as popular as they once were.
Another sort of cell is called a button cell. These come in a
variety of sizes from the very tiny ones used in ladies watches
to the coin size ones used in computers and a lot of portable
equipment.
The smaller button cells have a lot more type numbers than other
cells. It seems that every manufacturer has its own type number
for a particular size. The large coin size cells have a more common
set of numbers that describe what the cell size is. These are
numbers like 1620 and 2025. The
first two digits give the diameter in millimetres. The second
two digits give the thickness in tenths of a millimetre. The coin
size cells normally have a voltage of 3 volts. Almost all other
non-rechargeble cells have a voltage of 1.5 volts.
All button cells have the outer case as a positive connection
and the smaller disk on the other side as a negative connection.
Technically a battery consists of two or more cells as shown with
the 3 cell 4.5 volt flat battery.
Rechargeable cells in the AAA, AA, C and D sizes
have a voltage of around 1.2 volts. Five rechargeables are needed
often to replace four non-rechargeables to provide six volts.
There is also another type of cell which is only found in a battery of cells these days. It is the a cell in a car or motorcycle battery. It is rechargeable and has a voltage of two volts. Most car batteries have six cells and have a voltage of 12 volts.
The electricity obtainable from cells and batteries is called direct current or DC. It means that it flows smoothly all the time and only changes as the power in a cell or battery starts to decline.
2 Alternating
Current
The electricity from wall sockets is quite different. In Europe
it is around 230 volts and in North America 110 volts or 220 volts.
Wall socket electricity is quite unlike the electricity from batteries.
It changes at 50 times a second in Europe and 60 times a second
in North America. The electricity changes because it is easier
to send changing electricity from place to place than electricity
that doesn't change as comes from batteries. Changing electricity
is called alternating current or AC.The illustration shows equivalent
DC and AC voltages. The DC and AC shown are reckoned to be similar
in power when they produce the same effect from a heater or a
household lamp. Heaters and lamps work the same with electricity
going from A to B and B to A.
AC can be transmitted
from power stations to people's houses easily because it works
with a device known as a transformer.
A transformer is made with two windings of wire and an iron core.
A current through a winding around an iron core will make it into
a magnet. An alternating current through a winding around an iron
core will make the core into a magnet that keeps changing with
the changing current. A magnet that keeps changing will create
a current in a winding wound around it. A transformer usually
has a large and a small winding. A alternating current at a high
voltage in the large winding will create an alternating current
at a low voltage in the small winding. The same also works in
reverse. The illustration shows a symbolic impression of a higher
voltage to a lower voltage transformer.
3 Electricity
Transmission
The transformers used by electricity
supply companies are very efficient so that very little power
is lost in changing a low AC voltage to a higher one or from a
high AC voltage to a lower one. The reason why transformers are
used is because power is lost when supplying electricity through
wires. The amount of power lost increases with increasing current.
The amount of power available is equal to the voltage times the
current. If the voltage is doubled, the current is halved. The
power lost by halving the current is reduced to one quarter the
loss at the original current. Electricity companies arrange that
electricity is transmitted at very high voltages on wires mounted
on large towers or pylons for larger distances. The voltages used
normally range between 100,000 volts and 500,000 volts.
I have used the terms volt and voltage without explaining them so far. The term Volt in electricity is equivalent to pounds per square inch in air pressure. It is the pressure or force which can drive electricity along a wire. The higher the voltage, the higher the electrical force. The amount of electricity flowing through a wire as a current is measured in Amperes or more usually Amps. The amount of electrical power used by an electrical appliance is measured in Watts. Domestic electric light bulbs are rated in watts. A typical car headlamp bulb is rated at 48 watts. As a car usually has a 12 volt battery and electrical system, the current drawn by a 48 watt headlamp bulb is 4 amps. 12 x 4 = 48. Note that a car headlamp bulb is rated at 48 watts at 12 volts. A 100 watt domestic lamp bulb for room lighting is rated at 230volts in Europe or 110volts in North America. That is to say the lamp will consume 100 watts at the rated voltage. The car headlamp runs with DC and the domestic lamp runs with AC. In practice this makes very little difference to the way they produce light. The domestic lamp actually flickers 100 or 120 times a second. This is too fast for the human eye to notice.
Wall socket alternating current is what it says. It changes 100 times a second in Europe. That is to say it changes from positive to negative 50 times and negative to positive 50 times every second. The negative and positive changes are taken in pairs. One pair forms a cycle of changes. European electricity has 50 cycles of changes every second. In my young days the frequency of AC changes was called cycles per second. Later the term Hertz was used instead. European electricity is 50 Hertz (or Hz) and North American electricity is 60Hz.
4 Working With
Electricity
I have written only about electricity
so far. I have not mentioned directly what causes the current
to be limited. The term used is called resistance. Resistance
is measured in ohms. The symbol for ohms is the Greek letter omega
whick looks like this
. The symbol can be imagined as showing a little circuit
going around a loop. The relationships between Voltage, Current
and Power have been explained.
The symbols are
V for Voltage in Volts (V), I for Current in Amps (A), R for Resistance
in Ohms (
) and W for power in Watts (W). The names for
these units come from famous workers in the fields of electricity
and power.
Alessandro Volta gave us the Volt; André Marie Ampere gave us the Amp; Georg Simon Ohm gave us the Ohm and James Watt gave us the Watt.
The relationships between these units are simply expressed in a form of algebra where the symbols have a fixed meaning. The I for current means the current at the Instant. The A is shorthand for Amps. (I didn't devise the symbols and letters but we have to get used to the ones that everyone uses now.)
V = I x R; I = V/R; V/I = R; V x I = W; V²/R = W; I² x R = W; V²/W = R; W/I² = R; W/I = V; W/V = I;
These symbols and
letters are seen in different places as follows:-
A cell is 1.5V; A fuse or circuit breaker is 30A; A lamp is 100W;
A resistor is 10
.
Now I have shown you the symbols and their relationships I will
go back to the wall socket electricity for a moment. In Britain
the wall sockets in a house or flat are now all connected together
in a circle. This is known as a ring main connection. Each socket
is rated so that it can supply 13 amps at 230 volts. The fuse
or circuit breaker for the ring main is usually rated at 30 amps.
It is assumed that not all sockets will be used at full power
at the same time. An electric cooker has a fuse or circuit breaker
rated a 45 amps.
A single bar electric
heater is rated at 1,000 watts. At 230 volts the current it uses
is 4.35 amps. If the wires between the heater and the source of
electricity outside the house have a resistance of 1
, The actual
voltage seen by the heater will be 225.65 volts.
(4.35A x 1
= 4.35V;
230V - 4.35V = 225.65V)
This loss is not critical. The power lost in the wire is 18.92 watts.
(4.35A² x 1
= 18.92W)
Let us say that
the length of the wires between the source and the heater is 50
metres. Then a comparison can be made between the losses made
between a power station 50 kilometres away and the heater. If
all the wire was the same, the resistance between the heater and
the power station would be 1,001
. If the voltage output from the power station was
230volts, more power would be lost in the wires than the heater.
The heater resistance
is V²/R 230²/1000 = 5,290/1000 = 52.9
.
The total resistance is therefore 52.9
+ 1,001
= 1053.9
.
The heater's share is 52.9
/1053.9
= 0.0502 (about 1 twentieth) of the total voltage
(52.9
/1053.9
x 230V
= 11.54V)
The result would be that only around 11.5 volts would be available
at the wall socket.
218.5 volts would be lost in the wires.
Now imagine that
the power station uses a transformer to change 230 volts to 230,000
volts for the 50 kilometres and another transformer to change
230,000 volts down to 230 volts near the house. The resistance
of the wires between the transformers is still 1,000
.
The current between the transformers is 4.35A/1,000.
(If the voltage is multiplied by 1,000, the current is divided
by 1,000.)
The loss is therefore 1,000 x 4.35/1,000 = 4.35 volts from 230,000
volts.
The transformer that normally changes 230,000 volts down to 230
volts now has 299,995.65 volts to change down.
This system of supply would mean that 0.00435 volts are lost between
the power station and near the house. The heater has lost 4.35435
volts instead of 218.5 volts.
I have used easy
figures here to simplify things a bit but I hope that you can
see that transmitting electricity at very high voltages reduces
the losses between power stations and consumers. In practice,
the transformers used for electricity distribution are only around
97% efficient. On the other hand the wiring between the power
station's transformers has a much lower resistance than 1,000
. Around
90% of the power generated gets to consumers.
The transformers I have mentioned convert electricity into magnetism
and magnetism into electricity. They only work with alternating
current. A changing current creates a changing magnetic field.
A changing magnetic field creates a current in a wire near it.
An unchanging magnetic field does nothing.
I repeat this
for those who have other ideas.
An unchanging magnetic field does
nothing.
Note:
In the foregoing description I have found a fault with Firefox.
There is no way I have found to insert the omega symbol in
the text with the symbol font found in Windows. I have tried to
use a small image instead.
I trust that it will appear correctly in your browser.
5 Magnets
Magnets used for sticking on fridges
or for picking up iron and steel objects do not have changing
magnetic fields and therefore do nothing except attract iron and
steel objects. They do not consume any power or generate any power.
A magnet is no more than a form of special lever. Unless it is
used in conjunction with a source of mechanical power and an electrical
conductor, it can do nothing to produce electricity.
There is an experiment that anyone can do with a good horse shoe
shaped magnet.
Start by putting a dressmaker's steel pin next to one pole of
the magnet. Then attach a second pin onto the first pin. Then
add more pins to the chain until you can't get any more to stick.
The end of the chain of pins can now be stuck to the other pole
of the magnet.
No try to establish
a second and possibly a third chain of pins between the poles
of the magnet. Now see if it is possible to make two chains stick
together. You will find that they always push each other apart.
Remember this when thinking of the experiment that you may have
done at school. This is where a sheet of paper is laid over a
bar magnet and iron filings are sprinkled onto the paper.
The iron filings form chains like the pins did on the horse shoe
magnet. Each chain of filings is a complete induced magnet. Magnets
of the same polarity repel each other. The chains of iron filings
are all of the same polarity. Their mutual repulsion makes them
stay separate from each other creating the appearance of lines.
Thus it is ludicrous to infer that t
he
lines produced by the chains of filings have anything to do with
lines of force. If the iron filings are demagnetised and used
again, the pattern they will produce will be very similar to the
first pattern. However, it will be seen that the lines are in
different positions. Where lines occur is just a matter of chance.
No matter how many times the iron filings on a piece of paper
over a bar magnet experiment is performed, no two patterns will
be the same.
In more than 50 years of working with electricity and magnetism I have never encountered a device which can detect a magnetic line of force. Magnetic lines of force are just as real or unreal as gravitic lines of force or contours on a map. Anyone who refers to magnetic lines of force in any explanation concerned with astronomy is showing that he or she is ignorant of the properties of a magnet or magnetism.
Electric currents
that are not in wires.
The world is changing and cathode ray tube (CRT) television sets
are being replaced by flat screens operated by liquid crystal
displays or plasmas. However, as CRTs are still a relatively common
sight in people's homes, a brief mention of how they work for
television is appropriate. A CRT is more or less conical with
the base of the cone being the viewing screen. The apex of the
cone is extended by a short tube. At the end of the tube are the
connections to its heater and the control electrodes. The heater
makes the cathode produce electrons. The electrodes have high
voltages applied to them which attract the electrons towards the
screen in the form of a beam. Around the tube at the apex of the
cone are wire coils. These coils have currents passed through
them to create the magnetic fields which control the electron
beam used to produce the display. The image on the screen is made
up of lines. The PAL system uses 625 lines and the NTSC system
uses 525. The lines are created by moving the electron beam rapidly
from side to side while making it move less quickly downward.
In Europe a field
of lines is created every 25th of a second. In North America a
field is created every 30th of a second. The coils above and below
what is known as the neck of the tube create a vertical
magnetic field which deflects the electron beam horizontally.
The coils on either side of the neck create a horizontal
magnetic field which deflects the beam vertically. Note
that this shows that electrons always move sideways across a magnetic
field. They never move along the axis of the magnetic field where
the lines would be if there were any. Electric currents and magnetic
fields are ALWAYS at 90 degrees with respect to each other.
The electron beam in a CRT is directly comparable to a stream
of ionised gas. An ion drive for a space vehicle operates in the
same way as a CRT.
Protons behave in the same way as electrons in magnetic fields
but in the opposite direction. Protons are roughly 1800 times
heavier than electrons. The deflection of a proton beam would
be only 1/1800 the deflection of a comparable electron beam in
the same magnetic field. This factor is of great relevance when
ionised gases in space are considered. The momentum of a moving
particle is equal to ½MV². Thus the momentum of a
proton is 1800 times that of an electron. The density of protons
in the solar wind at the Earth's orbit is around 5 per cubic centimetre.
(Protons are only counted when they are not neutralised by electrons.)
Protons survive the journey outward from the sun much better than
electrons can. Their masses mean that they are much less deflected
by magnetic fields on their outward path than electrons and their
momentum enables them to survive more collisions than electrons.
The proton biased solar wind is a positive current. Currents in
wires are made up of electron movements and are always negative.
The solar wind interacts with the Earth's rotating atmosphere.
In consequence a positive proton current is set up as a ring around
the Earth. This current creates a magnetic field with an axis
roughly in line with the Earths rotational axis. It
creates a south seeking magnetic pole near the Earth's north geographic
pole. North and south seeking magnets attract each other. Thus
the north seeking end of a compass is attracted to the south seeking
magnetic pole near the north geographic pole. This ring current
magnetic field is accepted as being in existence by even doubtful
astronomers. The magnetic field acts as a shield against ionised
particles. As seen from the sun, the axis of the field is almost
vertical. Particles that encounter the magnetic field are deflected
sideways around the Earth. Positively charged particles tend to
join the ring current. Negatively charged particles tend to weaken
the ring current.
The Earth's magnetic field is affected by solar flares which temporarily
cause more protons to be trapped by the Earth's atmosphere. The
ring current is increased causing an increase in the strength
of the Earth's magnetic field. Solar flares are not steady outputs
from the sun. Their strength fluctuates at a low frequency of
the order of 1 to 3 hertz. The magnetic field caused by the ring
current is densest near the north geographic pole and is almost
vertical with respect to the Earth's surface. It just so happens
that in Canada and Finland that the electrical power grids are
organised using horizontal wires. The magnetic field that fluctuates
at a low frequency induces currents into these wires at the same
low frequencies. The transformers used to distribute the electricity
in Canada and Finland are designed to operate at 60 and 50 hertz
respectively. They cannot cope with high currents around 3 hertz.
In the past the electricity supply companies have had their distribution
equipment ruined by the low frequency currents that follow a solar
flare. Even now these electricity suppliers have to take drastic
steps to minimise the damage whenever a solar flare has been detected.
Here I will make a short digression. Petrol (gasoline) driven
cars use a spark coil to ignite the fuel in the car's cylinders.
The spark coil works by applying a current to a low resistance
winding of the coil, producing a strong magnetic field in its
core. The current is switched off causing the magnetic field to
collapse rapidly. This induces a current in the original coil
and a secondary coil. The secondary coil has many more windings
than the original coil. The current in both coils has nowhere
to go because neither are connected to a circuit. A capacitor
(condenser) across the contacts which switch the first coil on
and off handles the small voltage generated across the first coil.
An extremely high voltage is developed across the secondary coil.
It takes the path of least resistance and causes a spark across
the contacts of a spark plug. I have explained that a connected
circuit will allow a high and possibly damaging current to pass
in an electricity grid system. An open circuit where there is
no connection to anything will cause a very high voltage to be
generated. The high voltage will create a spark. The contacts
of the switches used in an electricity grid system are usually
2 or more feet apart when the switch is off. During the effects
of a solar flare the voltages generated can create sparks that
will jump several feet. The electricity suppliers have to try
to protect the switches as much as the transformers when a solar
flare occurs.
There are people who claim that the Earth's magnetic field is
created by moving metal within the Earth. If a magnetic field
was generated by this means and constituted most of the magnetic
field strength observed, the variations caused by solar flares
would have little effect on power transmission systems. It can
therefore be concluded that most of, if not all of the magnetic
field observed is generated through the action of the Earth's
rotating atmosphere and the positively biased solar wind.
Additionally, the moving metal theory for the source of the Earth's
magnetism is in direct conflict with a basic law of electricity
and magnetism called Lenz's Law. A current induced in a conductor
by a changing magnetic field will create a magnetic field in opposition
to the current inducing magnetic field.
In 1869 there was
an enormous solar flare. It had the effect of creating sparks
in the telegraph equipment used at the time across the USA. The
1869 flare had a great effect on the aurorae. Aurorae are caused
by the outer atmosphere being ionised. The shape of the Earth's
magnetic field is comparable to the surface of an apple. It is
nearer the centre of the Earth at the poles. Thus ionised particles
from the solar wind are not deflected away by the field at higher
altitudes and can affect the outer atmosphere around the poles
much more than nearer the equator where the magnetic field is
spread further away from the centre of the earth.

If an apple is looked at with the stalk upwards, a deep conical
depression can be seen around the stalk.
The magnetic field at the Earth's magnetic poles has a very similar
shape. Particles with enough mass are often attracted to the Earth
by gravity in the vicinity of this part of the magnetic field.
They are deflected sideways by the magnetic field as they descend
towards the Earth, falling in a spiral. They travel quite quickly
in the upper atmosphere but slow down as they get nearer the Earth's
surface because of air resistance. These particles create a sort
of radio signal that is in the audible range. The radio noises
they make have been given the name of 'whistlers'.Whistlers always have a falling musical tone.
It is the whistler phenomenon that has given some astronomers
the idea that charged particles spiral around magnetic lines of
force as they fall towards the Earth. There are no lines of force.
The particles spiral around a magnetic conical well as they descend.
The second apple
image has a circle to represent where the aurorae are seen from
space - still us
ing the apple shape
to illustrate the shape of the magnetic field near the magnetic
poles. I conclude from knowing the shape of the magnetic field,
and seeing images of aurorae from space, the aurorae are as near
the Earth as the magnetic field will allow ionised particles from
the solar wind to get. The region lower in the depression is shielded
from the solar wind so no visible ionisation can take place within
the circle. Further out the Earth's atmosphere is too diffuse
to interact with the solar wind to a significant extent unless
there is a big solar flare.
Astronomers frequently describe solar phenomena in terms of magnetism.
The magnetism is claimed to be responsible for the appearance
of sunspots and prominences. It is the magic medium that
has no obvious source yet astronomers say it does
almost everything seen on and around the sun.
Magnetism cannot arise by itself in any form of electrics or electronics
I have ever heard about. It is an astronomer's grossly misleading
label for what on Earth would be called vulcanism. There is an
almost limitless amount of thermal energy in the sun to cause
vulcanism. The temperatures at or just below the sun's visible
surface are so high that all the gases are ionised. Outer electron
shells of atoms float free of the nuclei at these temperatures.
Many fall back and emit the photons that create the photosphere.
Most electrons are affected by the magnetic fields that exist
in abundance around the sun's photosphere. The sun is an immense
ball of gas. It has no surface that is in any way comparable with
the surfaces of the inner planets. However, just for the purpose
of explanation I will refer to the visible surface or photosphere
as if it was a surface of a liquid. So when I use the word surface
it is only intended to mark a convenient boundary between the
transparent atmosphere and a region which is invisble below the
photosphere.
The sun emits heat
in enormous quantities. The upwelling of superheated gases cause
the granular appearance seen at the apparent surface. There is
some similarity to the surface of boiling water. The physical
processes are similar. Hot gases are bursting forth from below.
The gases that burst forth from the depths of the sun are highly
ionised. A moving ionised gas is an electric current. A property
of every electric current is that it generates a magnetic field
around itself. The magnetism is an effect caused by the combination
of vulcanism driving the gase
s as
a current and the high temperatures of the gases emitted. The
behaviour of a jet of ionised gas is directly comparable to a
jet of electrons in a vacuum as in a CRT. Both are currents surrounded
by magnetic fields. A magnetic field always takes the shortest
path possible. The effect of this is put to good use in a CRT.
The magnetic field around the electron beam constricts it down
to an incredibly thin jet. When this jet hits the CRT's phosphor
screen, the jet creates a small spot. A jet of ionised gas emitted
from the sun forms a large current and a consequently strong magnetic
field around the jet. The magnetic field is constrictive and helps
to keep the jet in a relatively narrow path. The emitted gas has
mass and the sun has a gravity field that is 28 times as strong
as Earth's gravity. In consequence most emitted jets fall over
and drop back towards the sun's surface. The shape of the arc
formed is not unlike the arc of water squirted from a fire hose.
There is a difference. A fire hose jet spreads out as it falls.
An ionised gas jet keeps its shape because its magnetic field
maintains the constriction throughout the path of the jet.. An
ionised jet of gas still retains most of its upward speed in a
downward direction when it meets the sun's surface. A lot of the
material and energy that created the jet is returned to below
the sun's surface. This usually causes another jet to be emitted.
This second jet often has a parallel path to the original jet.
Parallel jets can be seen in the image of the sun in the left
quarter of the image. The jets seen edge on are clearly in parallel
pairs. The main arcs in the image appear to be jets going both
ways. (I presume that the white ends
of arcs are where they start from.) Where the second jet enters
the sun's surface it provides energy and material to support the
emission of the first jet. Images of the sun's surface show hundreds
of pairs of jets that presumably operate in this fashion. Moving
images taken over time show that these jets are relatively long
lived. This is why it is presumed that pairs of jets replenish
each other's sources of energy and material. It should be noted
that as a pair of jets operate in opposite directions, their magnetic
fields are opposite too. In this circumstance opposite circular
magnetic fields are mutually repulsive. Thus the pair of jets
can be near each other without interfering with each other as
their arcs of ionised gases travel in opposite directions. Note
that two close jets operating in the same direction will have
magnetic fields which join together, causing the two jets to join
as on
e.
The illustrations show sections through jets. The cross symbolises
the back of an arrow and the circle the point of an arrow to indicate
the directions of the jets. As with magnets, opposite fields attract
each other and like fields repel each other. The lower image shows
two jets attracted to each other that have not yet joined each
other. As said earlier, a magnetic field always takes the shortest
path.
These jet arcs are
described as magnetic loops in many astronomy books. A magnetic
field is no more visible than a gravity field. In other words
a magnetic field can never be seen. It is always at right angles
to the current that produces it. The heat flow from the sun is
generally radially outward. For a magnetic arc to be created,
there would have to be a very strong lateral movement of ionised
gas. As the arcs are frequently in pairs as I have shown, two
currents of ionised gas would have to flow laterally in opposite
directions towards or away from each other to support a pair of
arcs. As the arcs are visible, they can't be magnetic. No visible
medium except solid iron particles can follow the path of a magnetic
field.
Some emissions from
the sun are stronger than others. Some are so strong that they
can be seen from
Earth during an eclipse.
These are giant arcs of luminous gas and have their own name.
They are called prominences. I have already mentioned solar flares.
These are jets which leave the sun so fast that they exceed the
sun's escape velocity. Between flares of this type and the jet
arcs already mentioned are the prominences. The prominence shown
has a visible height above the sun's surface of at least 215,000
kilometres and extends around the sun's circumference 600,000
kilometres. In comparison the Earth is 12,756 kilometres in diameter.
The prominence as seen here is nearly 17 Earth diameters high
and nearly 47 Earth diameters in width. These are jets that do
not quite achieve escape velocity. Please note that the view here
does not show the parts of the sun where the prominence comes
form or where it goes to. These places are beyond the sun's horizon
in the image.
In astronomy books it is stated that prominences are caused by
magnetism. The source of the magnetism is never explained. I think
prominences are caused by vulcanism. The small jet arcs described
have magnetic fields around them that keep them flowing in discrete
rainbow like arcs. A prominence jet reaches a far greater height.
The prominence shown is enormous. A jet that is ejected radially
from a rotating body gradually becomes more and more subject to
the coriolis effect. In addition, the gases in the sun's upper
atmosphere rotate around the sun faster than those at the surface.
These two effects tend to drive the upward jet sideways. A second
factor affects the jet. As it rises upwards it decelerates. This
causes its effective current and its magnetic field to decrease.
The weaker magnetic field allows the jet to broaden in the less
dense atmosphere at the height it has reached. Near the top of
the jet's rise its vertical speed is low and its horizontal speed
is higher. As it still moves significantly it is still surrounded
by a magnetic field proporionate to its speed. Then the mass which
forms the jet is pulled back down towards the sun's surface. As
it descends its speed increases and so does the strength of the
magnetic field around it. The increasing magnetic field applies
increasing constriction to the jet so that it becomes almost as
narrow when it returns to the sun's surface as when it was projected
upwards. Its speed and mass are almost the same as when it was
projected upwards. It bores a hole in the sun's surface that is
comparable to the hole it came out from. As with the smaller arc
jets, energy and material is returned to a point somewhere below
the sun's surface. The energy and the material go down deep below
the surface and reach a point that is not very far from the energy
centre that was the source of the jet in the first place. The
energy source has a lot of energy and material returned to one
side of it. This causes the energy centre to be deflected a bit
to one side of its original position. As so much energy and material
has been returned to a point so near the source, the upward jet
is maintained but is slightly offset from its original position.
The returning jet is now also slightly further away from its original
starting point. The effect of the offset of the returning material
and energy is to drag the source hole in the direction of the
point where the downward jet returns to the sun's surface. As
the source hole moves, so does the destination hole move. It is
continuous creeping process.
To get some idea of the energy needed to create the prominence
illustrated I offer some basic calculations. The sun's gravity
is around 28 times as strong as the Earth's gravity. The Earth's
gravity gives an acceleration of 9.81 metres per second per second
(9.81m/s²). The sun's gravity is therefore 28 x 9.81 = 274m/s²
(approx).
The formula that relates velocity, acceleration and distance is
v²=u²+2aS. The velocity v equals the square root of
the sum of the initial velocity u plus twice the acceleration
a times the distance S.
The distance is 215km or 215,000,000 metres. The initial velocity
is nil. The sum is therefore
SQRT(2 x 274 x 215,000,000)
= 343,249 metres per second.
Many of us prefer to think of speeds in miles per hour or miles
per second.
343,249m/s = 767,827mph or 213 miles per second.
This calculation assumes the speed of an object if if fell towards
the sun from a height of 215km and there was no air resistance.
This is the same speed that that an object would have to have
if it was launched from the sun's surface to reach a height of
215km and there was no air resistance.
In comparison, the international space station orbits the Earth
at around 5 miles per second.
I have used this calculation to enable the reader to get some
idea of the enormous energy involved in a solar prominence.
I think that prominences are directly associated with sunspots. There are several observations that provide links between the two phenomena. I said that a prominence is a jet that did not quite make escape velocity. That is a simplification. It is likely that a part of the jet reaches escape velocity while most of it does not. If such a jet arises from a sunspot, and some of it reaches escape velocity, It could explain why the solar wind is stronger when sunspots are present.
It is said that sunspots are cooler than the surrounding photosphere. If a sunspot is a source of a powerful jet, the gas in the jet will be highly ionised. Light in the form of photons is generated when electrons in an atom fall towards the nucleus from a higher energy level to a lower one. A jet of the form which could create a prominence would have to have an enormous amount of energy to launch it. The energy is supplied in the form of heat. At very high temperatures atoms lose their outer electron shells. In such a super heated state, few electrons will fall towards the nuclei and give off photons. The gas in this state will appear to be relatively dark visibly and will be comparably 'dark' in the infra red and heat bands. As radiant light and heat are transmitted in the form of photons, photon scarcity will give the impression of relative coolness corresponding to the relative dimness. Sunspots are presumably viewed through the cores of jets. As a jet rises it decelerates causing the magnetic field around it to become weaker and less constrictive. The jet expands and cools. I think that the apparent lower temperature of sunspots is partially due to the fact that they are observed through cooler gas. Prominences can only be seen clearly when the sun's photosphere is obscured by an eclipse. This is because they are far less luminous than the general photosphere. This tends to suport the idea that the ionisation of the gas which forms them is not conducive to electrons falling back towards nuclei to generate photons. The replenishment cycle I have referred to for prominence jets causes the source and destination to move while maintaining the jet for a time. This movement could be the cause of the way sunspots move.
Sunspots always
occur in pairs. However, it will generally be noted that one spot
is a relatively neatly bounded dark patch while the other is very
frequently made up of a larger jagged spot with a lot of smaller
spots around it. If the jagged spot is the destination of a descending
jet, its appearance is comparable to the effect of a garden hose
squirted onto a muddy surface. The descending jet breaks up a
bit as it approaches the sun's surface into a main jet with several
subsidiary jets.
The points I have mentioned here are minor when considered individually
but seem to provide a strong link between solar prominences and
sunspots when considered together.
If it is assumed that a pair of sunspots form the source and destination
for an ionised jet, the magnetic field
at the source will be circular counter clockwise and circular
clockwise at the destination. (This is based on the right hand grip rule which was
invented when an electric current was presumed to go from positive
to negative in wires.) In this instance, the current in question
is really a positive current of protons or positively charged
particles. If a theoretical right hand could grip the upward jet,
the thumb shows the direction of the jet and the fingers show
the direction of the magnetic field. The same rule applies to
the downward jet.)
The idea that one sunspot has a north polarity and the other has
a south polarity has no basis. They are opposite it is true but
neither is like a conventional magnet pole.
Where I Think
Astronomers Go Wrong
I have wanted to explain the errors
in a lot of what astronomers have written in books about magnetic
fields in space for a long time. I thought that I would do some
checking first to find out why astronomers seem to have such silly
ideas about magnetism. I decided to check on Clerk Maxwell's equations.
They are covered very well in Wikipedia.
Many people based their ideas on the writings of the early Greek
philosophers before the works of Galileo were published. The Greek
philosphers (in general) claimed that the Earth was at the centre
of the universe. They also claimed that heavier objects fell faster
than lighter ones. Galileo found that the Earth was not at the
centre of the solar system. He also did some experiments to check
if heavier objects fall faster than lighter ones. He found that
they didn't.
Before I started
checking on Maxwell's equations I knew that astronomers used them
as a basis for working in the same way as people made assumptions
about the Earth's position in the universe and the falling speeds
of weights - before Galileo.
I have heard it said by astronomers that Maxwell proved that electricity
and magnetism are equivalent. This may be so in terms of mathematics
but not in the practical world. Some extremely elementary
experiments will show how different the two phenomena are. Please
note that I am not referring to electromagnetism here. From their
writings it seems that many astronomers do not differentiate between
magnetism and electromagnetism. Electromagnetism can only exist
if there is a continuous change in electric and magnetic fields.
There is no electromagnetism in a static magnetic or electric
field.
The major difference
comes between electricity and magnetism because electricity in
its usual sense implies a current which is a form of movement.
An electric current cannot flow unless there is a source of energy
to generate it. In wires, a current is exclusively carried by
electrons. In semiconductors it can be carried by either electrons
or holes. In gases it can be carried by protons or electrons.
There is no magnetic equivalent of a current.
A magnetic field has some properties which are similar to gravity.
Firstly it is normally regarded as a static state of affairs.
Magnetism attracts ferrous objects while gravity attracts anything
that has mass. Both forces operate through nothing or whatever
the current name is in physics for the luminiferous ether. Einstein
called it the spacetime continuum. (I will call it spacetime here.)
Gravity affects Einstein's spacetime as can be seen in the lens
effect caused by stellar bodies. Magnetism affects light to cause
the splitting of spectrum lines. I therefore conclude that both
magnetism and gravity cause stresses in spacetime. The stress
in spacetime caused by a magnet is an indication of a magnetic
field's property of taking the shortest possible magnetic path.
Magnetism is unlike gravity in that it is always bipolar or circular.
The magnetic field of a fixed magnet always acts between its north
and south poles. Gravity acts between any two or more bodies that
have mass. A magnet works on ferrous objects because a ferrous
object provides a shorter magnetic path through itself than free
space does. There is no equivalent to a ferrous object in a gravitic
field.
The nearest equivalent
to a conductor in a magnetic field is a keeper bar across the
poles of a horse shoe magnet. Even so, there is no equivalent
of a current flow in magnetism. A horseshoe magnet with or without
a keeper in place is always in a static situation. Now it is commonplace
to find magnets used in many situations. Whatever magnet you find,
it will always have the same properties. It will consume no power
to maintain its magnetism. At the same time it cannot be used
as a source of power on its own. There is no energy in static
magnetism.
There is a very general rule about energy. There may be losses
but nearly every form of energy can be converted into any other
form of energy. James Prescott Joule found that mechanical energy
could be converted into heat. James Watt and others showed that
heat could be converted into mechanical energy by using steam.
Mechanical energy can be converted into electrical energy with
a generator. Electrical energy can be converted into heat energy
with a resistor or into mechanical energy with a motor. I have
yet to hear of a process that can change mechanical or heat energy
into magnetic energy or can convert magnetic energy into another
form of energy. Is there a way of converting gravity into some
form of energy? Magnetism and gravity have similarities. They
are forces that contain no energy in themselves.
An electric current through a wire creates a static magnetic field
around the wire. If a wire is surrounded by a static magnetic
field, no current is induced in the wire. To generate a current
in the wire, either the wire or the magnetic field must move.
This means that mechanical energy must be used to do the moving.
I hope that you can see from what I have written, electricity
in the form of a current has no equivalent in magnetism. How can
a moving phenomenon be equated to a static one? The interpretation
of Maxwell's equations which says that magnetism and electricity
are interchangeable is false.
If there is a change
in an electric field potential, it must be caused by some agency.
In practice, a change in electric field potential constitutes
an electric current. If the change is fast enough, an electromagnetic
stress is caused in spacetime. A radio wave is generated. However,
most of the errors that astronomers make are based on the assumption
that an electric current and a static magnetic field are interchangeable.
They also confuse electromagnetism (radio) with the separate phenomena
of moving electric currents and static magnetism.
Maxwell published
the equations on which many astronomers depend in 1895. The electron
was not discovered as an electric charge carrier until 1897 by
J.J. Thomson. The relationship between electrons and photons was
not discovered until much later. (I don't want to get involved
with quantum mechanics here.)
The situation as I see it concerning the errors that astronomers
make is to take what Maxwell said as being practically true when
it may have been only mathematically true. None seem to have taken
the trouble to look beyond the mathematics to the real world.
They have never played with a battery, a small bulb, some wires
and a compass.The battery, wires and bulb can create an electric
current that has a visible result. There is no construction with
a fridge magnet or any other magnet that can do anything comparable.
The only way that a magnet can be persuaded to do anything is
when it is used in conjunction with mechanical energy. The
easiest way to demonstrate this is with a small electric motor
of the sort used in toys. The motor connections are used in place
of the battery in the check with the wires and the bulb. When
the motor is connected, nothing happens. Then, if the shaft of
the motor is spun between thumb and forefinger, the bulb may glow
briefly. The magnet in the motor can induce a current in the coils
of the motor's armature when mechanical energy is supplied. If
there is no input of mechanical energy, a magnet does nothing.
Astronomers also seem to show almost complete ignorance about
what a magnetic field is like.
Some astronomers may have put iron filings on a piece of paper
laid over a magnet and seen the pattern. The illustration gives
a rough idea of the appearance of the lines that are seen. I think
that none
have done it twice to check if
the lines that appear occur in the same places. If the iron filings
experiment is repeated many times it will soon become clear that
there are an infinite number of lines or none at all. The visible
lines are a property of the induced magnets created from chains
of filings. All induced magnet chains are effectively magnets
of the same polarity and therefore mutually repulsive. They therefore
create the appearance of lines.
No detector I know about can detect a step transition between levels of magnetic field strength. Looking for magnetic field lines is as sensible as using an altimeter to detect contour lines as one climbs a hill. Yet there countless examples of astronomers ascribing properties to magnetic field lines as if they had a real existence.
It seems to be a case that astronomy students have accepted what their lecturers have told them without doing a single test to check the facts.
I never thought
of including a quotation but I have found one from Galileo, reviewing
William Gilbert's treatise on magnetism: "I extremely
praise, admire and envy this author. I think him moreover worthy
of the greatest praise for the many new and true observations
that he has made, to the disgrace of so many vain and fabling
authors, who write, not from their own knowledge, but repeat everything
they hear from the foolish vulgar, without attempting to satisfy
themselves of the same by experiment, perhaps that they may
not diminish the size of their books."
In the context of this essay I would change Galileo's 'hear from the foolish vulgar" to 'have read in other books' or "have heard from a university lecturer". I also think that the reference to William Gilbert's treatise on magnetism is appropriate to what I have written here.
Now, hopefully, the reader will be able to see that some extremely simple experiments will show beyond any possible doubt that an electric current and magnetism are not the same as each other in practice. Maxwell may have been a brilliant mathematician but his knowledge of practical electricity and magnetism was almost nil.
I cannot say that
all of what I have written proves that what many astronomers have
written is misleading. However, I am sure that I have shown enough
to make any unbiased person query the original research on which
many claims by astronomers are made - particularly in respect
of magnetism. I wonder how any astronomer can produce a demonstration
to show that magnetic lines of force exist.
Wilf James
6th February 2009
Updated 8th June 2009
Credits (in this draft)
Some images have been freely taken from sources found on the internet.
The images of the sun are from NASA.
The other images are drawings I have produced myself.
