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 sockets. (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.
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.
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
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/W 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.
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.
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 the 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.
6 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 used in some 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.
7 Positive Currents
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.
8 Solar Flares
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.
9 A Stupid Idea
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 moving conductor by a magnetic field will create a magnetic field in opposition to the current inducing magnetic field.
In 1859 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 1859 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 using 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.
11Astronomers' Misuse of the word Magnetism
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. 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.
12 Visible Features
on the Sun
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 gases 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 one.
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.
13 The Opposite
of Harry Potter's Invisibility Cloak?
These visible 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.
14 The Big Ones
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 from 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 proportionate 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 215,000km or 215,000,000 metres. The initial velocity is nil. The sum is therefore
SQRT(2 x 274 x 215,000,000)
= 343,249.18 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 213.285 miles per second.
This speed is equivalent to circumnavigating the Earth in less than two minutes.
This calculation assumes the speed of an object if it fell towards the sun from a height of 215,000km 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 215,000km and there was no air resistance.
In comparison, the international space station orbits the Earth at around 5 miles per second.
I have only referred to speed so far. I can't say how much mass is involved in a prominence but I can give an idea of the energy involved in projecting a mass of one kilogram to a height of 215,000 kilometres above the sun's apparent surface. We can work out the energy in easy stages. The mass of one kilogram will have a momentum of ½ × M × V × V or ½MV². Since M is 1kg the momentum is V²/2.
V = 343,249.18m/s V² = 117,819,999,570.672. V²/2 = 58,909,999,785.336 kilogram-metres per second.
There are 76.04 kilogram-metres per second in a horsepower.
The power to launch 1kg to 215,000 kilometres above the sun is therefore 58,909,999,785.336/76.04 = 774,723,827 horsepower.
Multiply this figure by however many kilograms of mass you think is in a prominence to find out how many horsepower are needed to launch a prominence like the one in the image.
I have used these calculations 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.
16 Are Cool Prominences Hot?
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 support 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.
17 A Link Between
Sunspots and Prominences?
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.
18 The Magnetic Field Around a Sunspot
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.
19 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 philosophers (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 oscillatory change in electric and magnetic fields. There is no electromagnetism in a static magnetic field or continuous electric current.
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. Magnetism is a property of an electric
current. The reverse is NOT true. There is no energy in a permanent
magnet. 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
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 one similarity. They are forces that contain no energy in themselves. I therefore think that astronomers who refer to magnetic energy have forgotten some elementary physics.
A steady electric current through a wire always 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.
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. Quantum theory states that energy
is in the form of small packets called quanta. These packets are
generally perceived as photons, the electromagnetic distributors
of light and heat. Electrons surround the nuclei of atoms at specific
energy levels. When an electron changes its position form a higher
energy level to a lower one, a photon is emitted. Photons have
strange properties. They act like particles and waves and a single
photon can apparently go through two apertures at the same time.
Maxwell knew nothing about electrons and photons when he stated
that magnetism and electricity were equivalent.
20 A Way to Show ths Difference Between Electricity and Magnetism
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.
21 An Attempt At Enlightenment
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.
22 Nobody Seems
to Have Checked The Facts
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 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.
6th February 2009
Updated 8th June 2009 and 19th November 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.