Quote from: Tom NapierNewman -- point by point
Part 1, Currents and field strengths http://www.phact.org/e/skeptic/newman.htm
Prepared by Tom Napier. Copyright © 1999, All rights reserved.
Introduction:
This document is one of a series which address specific errors made by Joseph Newman in his book, "The Energy Machine of Joseph Newman."
This section examines the connection between the current flowing in a solenoid, its number of turns and the resulting magnetic field and power consumption. It relates to the section of Newman's book which runs from page 297 to page 302 and, in particular, to the table on page 299. (Page numbers refer to the 8th edition.)
Nothing to dispute here.
Quote from: Tom NapierNewman claims:
1) That the current required to generate a given magnetic field can be reduced by increasing the number of turns in the solenoid.
This is of course true in that even a small current
MAY be set to produce a magnetic field with greater overall potential energy
AND strength.
Quote from: Tom Napier2) That the power required to generate a given magnetic field falls in proportion to the number of turns and tends to zero as the number of turns increases.
This is true for the amount of potential energy in the field, but not for the
DENSITY of it. Over time, a small amount of input power will result in a large amount of input energy. No matter how much you change the coil design, the amount of input power has inherent limitations in one's ability to make the field intensity of the coil greater.
HOWEVER, do not confuse field intensity with force, since field intensity is proportional to the square root of the potential energy density of the field, which in turn is proportional to the pressure of the field. That means to increase field intensity by x times increases the pressure by x^2, and on top of that, it fails to account for area to derive the force from this pressure, as well as the distance over which the force is applied.
Quote from: Tom Napier3) That this proves that the magnetic field "emanates from the atoms of the conductor and not from the current."
1 and 2 are not proof or even evidence of such an origin. It simply is coherent with the idea that the magnetic field potential energy must be derived from an interaction which can be assisted or even caused by the presence of charged particles (in this case atoms). Newman has claimed in his patent submission that charge flow through resistance determines the magnetic flux generated and that magnetic flux through resistance produces charge flow, which is not wrong at all, although his spoken demonstrations (notably as of late) implies that he ignores the influence of current.
Quote from: Tom NapierMy response:
Conventional physics states that the magnetic field intensity generated in the center of a hollow cylinder of a given length is a linear function of the total current flowing round the cylinder. It is not a function of the diameter of the cylinder provided its length is many times its diameter.
IT IS TRUE that current is a linear function with respect to field intensity in such a given coil.
HOWEVER, it is not true that this is linearly proportional to either power consumption or energy stored in the field. That is because power relies on voltage not just current while the energy stored in the field relies not only proportionally to the square of the field intensity but also the volume, since the field intensity is proportional to the square root of the field's potential energy density.
Quote from: Tom NapierPhysics also states that it is immaterial how the current flowing in the cylinder is generated.
However, what is not immaterial is the
WAVEFORM of the current itself, which has dependency on how the current is generated in the first place.
Quote from: Tom NapierThe total can consist of a high current flowing round the cylinder once or a small current flowing round the cylinder many times. Which is preferred is a practical matter, not a physical one. This has been known to be true for about 180 years. Thus Claim 1) is true and is in complete accordance with conventional physics.
Actually, by definition, preference entails a intention that may be aligned or not aligned with other people's generally accepted practices.
The person deciding what is to be preferred may do so for the sake of experimental research rather meeting the demands of an organization.
Quote from: Tom NapierNo power is required merely to maintain a static magnetic field. To establish a field in the first place requires a momentary input of power. This power is stored in the field and can, in principle, be recovered when the current is turned off. Until then, power is only needed to force the required current through the winding resistance of the solenoid. This power generates heat in the solenoid but does nothing else useful.
A static magnetic field is produced by
BOUND CURRENTS that arise from quantum mechanical principles. Although they have potential energy surrounding them based on a field, it cannot be a source of power. The reason why engineers design motors that incorporate induction between electromagnets and permanent magnets is that permanent magnets have higher magnetization. Magnetization is the amount of magnetic moment per unit volume. By crossing a field from a solenoid with a strongly magnetized object, such as a neodymium magnet,
A TORQUE is produced according to:
1) the square of the field of strength of the solenoid
2) the shape and size of the magnet vs. the shape and size of the solenoid interior
3) the magnetization of the magnetic object
Quote from: Tom NapierIt can be shown, see below, that this power does not depend on the number of turns of wire but only on the dimensions of the solenoid. It can also be shown that there is an minimum power required for any given field, no matter how big the solenoid is made. This shows that Newman's Claims 2) and 3) are incorrect.
You have no idea what the power output would be. In your analysis:
1) You have not defined the torque of the system.
2) You have not defined how quickly such torque can be produced and destroyed.
Quote from: Tom NapierThe analysis:
To make life simpler I'm going to assume square section wire of side "T" inches. The results can easily be corrected for round wire if one wants. (I am using "*" as a multiplication sign and, to avoid superscripts, I am representing exponentiation as repeated multiplication.)
Let's call the inside radius of the solenoid "P" and the outside radius "Q." Its height is "H." The cross-section of one side of the solenoid is thus a rectangle H by (Q - P) inches. Since the wire has an area of T*T the number of turns "N" in the solenoid is H*(Q - P)/(T*T).
The volume "V" of the solenoid is pi*H*(Q*Q - P*P). Its mass is this number times the density of copper which is 0.320 lb/cuin. Since the area of the wire is T*T its length "L," assuming no wasted space, is V/(T*T). This length of wire has a resistance "R" given by L/(T*T) times the resistivity of copper which is 0.63 micro-ohms per inch. The power needed to drive a given current "I" through the solenoid is its resistance multiplied by I*I.
Provided the diameter of the solenoid is smaller than its height the field strength at its center is proportional to N*I/H.
This is pretty straight forward as there is no disagreement with the scenario itself. However the conclusions lack precision, as follows:
Quote from: Tom NapierFrom these results one can show, see the appendix, that the power required to maintain a field strength of F Webers is:
W = 808*F*F*H*(Q + P) Watts.
-----------------
(Q - P)
This formula only shows the "field strength" in "Webers" when in fact the unit for field strength in Telsas is "webers/meter^2". Also, comparing power input to power output makes no sense without having knowledge of both. Once someone defines the actual force and velocities then can one calculate the
RATE of work being done.
The Weber is an SI unit, and in here it stands specifically for
MAGNETIC FLUX. The magnetic flux accounts for the area in which magnetic field intensity exists. While it requires the incorporation of area, it fails to account for the fact that the pressure in the field is proportional to the square of the field intensity. Thus, Webers must be squared first of all, thereby squaring both the differential area as well as the field intensity. But then you must consider the fact that once you have determined the field strength (measured in the SI unit
TESLAS) and squared it, you must multiply it by (1/2)*volume/magnetic constant to get the amount of potential energy stored in the field.
Quote from: Tom NapierThat is, the power required to maintain the given field is a function only of the field strength and the dimensions of the solenoid.
This says nothing about the fact that you must change the field rapidly to get any work done rapidly. Thus the electric field must be variable with time and space, and quickly so, to get much work done in a short amount of time. This need for swiftness is especially true for smaller electric fields which are typical of smaller motors. Keep in mind that with the magnetic field, both its flux and its strength are quantified using different SI units. The same separation of flux and strength applies for the electric field. The SI unit of electric flux is the call "volt-meter".
Turning on the coil increases its own potential energy. In fact, it increases the potential energy in the entire system
EXCEPT FOR THE SOURCE OF ENERGY since the potential energy is defined between interacting particles. It becomes clear that electrical potential energy with respect to
SUBATOMIC levels is
DILUTED while the potential energy of the
MACROSCOPIC level becomes more
EVIDENT, though the force per particle significantly affected becomes much weaker as the particles significantly affected increase.
The relationship between power input through electrical activity versus power output that is useful for motive power involves many physics parameters, and often it comes from energy that is not evident at the macroscopic level. After all, energy sources were understood after WORK was defined, as a result of the need to understand the nature of atoms, particularly in chemistry and nuclear physics. Electricity is not a root source of energy but is simply the common language by which all potential bound energy is converted into motive power. Electrical potential energy does not self-multiply and is a constant of the universe.
Quote from: Tom NapierIt is completely independent of the number of turns. As Q becomes much greater than P, (Q + P)/(Q - P) tends to unity. That is, for a given height of solenoid the power tends to a constant no matter how much copper one adds. Adding to the height increases the power needed. This directly contradicts Newman's Claim 2).
Increases in the number of turns for a given mass, shape, and volume of a coil consisting of the same conducting material increases in the inductance. To achieve this requires that the resistance to increase proportionally.
When given the same allocation for coil volume, both resistance and inductance scale proportional to the
SQUARE of turns, n.
In either case, a DC current will take nearly the same amount of time to reach some percentage of its final value, but this value for maximum current (voltage/resistance) will be lower for the high inductance, high resistance circuit. Given the same time frame (i.e. same frequency), it will consume n^2 times less power to generate n^2 times less torque.
As long as the person switches to higher gauge wire to fit in the exact same space and mass as the original coil, one will be decreasing the power density of the system
IF DC VOLTAGE IS KEPT THE SAME.
However, if one were to achieve the same amp turns of the system, one would have to increase voltages by the amount, n*(original power factor/final power factor) while currents would increase by n. The first reason is that between the two first cases, the second case requires that the current would fall by n^2 while the cross-section of each turn falls by n only. The second reason is that as one increases the DC voltage, the amount of time the motor spends on each rotation is reduced, requiring a briefer switching interval, potentially reducing the power factor. As a result, with the higher turns, it is possible to manage the same current density as the original coil with a voltage that is increased by a factor (n+ε) greater than the relative increase in turns (n). Under certain conditions, such a coil of the same volume can withstand higher power transmission with the same current densities.
By increasing resistance and inductance, the heat losses for the same current increase relatively by n^2. The benefit is that n^2 times as much work can be done per revolution (because of n^2 higher torque). Heat losses are also n^2 times as much per second in the same volume.
HOWEVER, because the voltage is increased by an amount greater than n,
RPM MAY INCREASE. Keeping this in mind, the increase of the energy lost per revolution may be just a factor less than n^2. Thus, heat losses per revolution
MAY fall faster than work done per revolution, as would be expected from reducing the power factor. Explained further...
In cases where input torque climbs faster than the shaft torque, the % of free-load rpm dropped under load will fall. As a result, such systems which already possess a lower power factor will be able to reduce the power factor faster than the voltages increase. The fact is that this will increase rpm slightly beyond a linear relationship will voltage, even under load, but only so slight.
In other words, altering the number of windings in an electric motor have many non-linear influences of performance, even when ignoring their orientation.
Quote from: Tom NapierA worked example:
One can increase the number of turns in a solenoid in two different ways. One can use thinner wire so that the new solenoid has the same dimensions and mass as the old one. Alternatively. one can add more turns of the same wire. This gives a solenoid having a much larger diameter and mass than before.
That is the scenario, so we don't question this.
Quote from: Tom NapierIn both cases the current can be reduced in proportion to the increased number of turns and the magnetic field will remain the same.
Your continued reference to the magnetic field without distinguishing magnetic flux vs. magnetic field strength undermines your arguments for those who have received accurate education of the workings of electromagnetism, especially for those with an extensive background in modern physics.
Quote from: Tom NapierLet us suppose that all solenoids are 10 inches high and have an internal diameter of 2 inches. That is, H = 10 and P = 1. We'll start with a reference solenoid which has an external diameter of 3 inches (Q = 1.5 inches) and which is wound with 0.1 inch wire. (Roughly equivalent to 9 AWG wire.) Obviously it has five layers of 100 turns each. That is, there are 500 turns. We are going to put 2 amps through it to get a field of 1000 A.turns. (Just for the record, the central field intensity will be 49.5 gauss or 0.00495 Webers.)
The volume of the solenoid is 39.270 cuin and its mass is 12.57 lbs. The length of the wire is 3927 inches and its resistance is 0.2474 ohms. Putting 2 amps through the wire requires 4 x 0.2474 Watts, that is 0.9896 W. That's our reference figure.
Case 1)
Keep the same solenoid dimensions and use thinner wire.
Let's use 0.025 inch square wire. (Roughly equivalent to 21 AWG wire.) Its side is a quarter of the previous wire so its area is a sixteenth. Since the dimensions of the solenoid are the same the number of turns has gone up by a factor of 16, that is we now have 8000 turns. To get the same magnetic field we only need a sixteenth the current or 0.125 Amps. The volume of the wire hasn't changed so its length must have gone up by 16. We now have 62832 inches of wire or almost exactly a mile.
The length has increased by 16 and the area has decreased by 16 so the resistance has increased by 256. We now have 63.335 ohms with 0.125 amps flowing through it. That's still 0.9896 watts or exactly as much power as before.
That is, changing the wire size has reduced the necessary current but has made no difference at all to the power. What has changed is the voltage required. In the original solenoid we needed less than half a volt to put enough current through the coil. The new coil takes a sixteenth the current and hence sixteen times the voltage or 7.9 V to be exact. In practice it is more convenient to drive a solenoid with 8 volts at 0.125 amps than it is to use a 2 A, 0.5 V supply.
As I explained before, this does not deal with the issue of output power at all.
Quote from: Tom NapierNote particularly that Newman's prediction that using more turns would reduce the required power did not hold up.
His view (Newman's view) of the magnetic field is that of a potential energy source. Your view of it so far lacks any sense of:
1) how much torque there ought to exist between magnetic components relative to the power being delivered to the device
2) how the speed of the motor influences the amount of power drawn as well the subsequent torque
Quote from: Tom NapierIn his table he assumes that the voltage driving the coil is a constant 10 V and derives the power from 10 times the current. As can be seen above, this is absurd. If you applied 10 V to the reference solenoid it would pass about 40 amps and probably melt.
It follows from your belief about this motor that current would have enough time to reach its full value. The truth is that with a large multi-layer solenoid of great mass, one would have a high ratio between of inductance over resistance. The result is a large charging time for the coil, which according to the patent, allows for delays in the circuit as much as
TWO SECONDS said to be proven when a light bulb was connected in
SERIES with the device. Even then, the resistive voltage drop of the light bulb was comparatively insignificant relative to that of the coil, much less its inductive voltage drop! This means that the current in a very massive inductor must be delayed significantly before it can reach the 40 amps you speak of!
Quote from: Tom NapierCase 2)
Let's keep the wire size the same but reduce the current to 0.125 A. We still need 8000 turns to get the same magnetic field. That is, at 100 turns per layer we need 80 layers of wire. That's 8 inches worth, the solenoid is now 18 inches in diameter. (2 inch central hole plus two 8 inch windings.) Its volume is now 2513.27 cuin and its weight a whopping 804 lbs, 64 times the mass of the reference solenoid. This is beginning to sound like a real Newman coil.
The wire is now 251327 inches long, that's almost 4 miles. It has a resistance of 15.834 ohms. If we put 0.125 A through it, it will dissipate 0.2474 Watts. This is a quarter of the dissipation of the reference coil.
You have the same problem here, but with a coil better resembling the properties of a Newman motor. Yet you made no significant improvement in your arguments here.
Quote from: Tom NapierA summary:
In case 1) where we went from 500 to 8000 turns but used the same mass of copper the power required was identical. In case 2) we went from 500 to 8000 turns. We used 64 times as much copper and reduced the power to a quarter. This obviously contradicts Newman's contention that the power required for a given field falls directly in proportion to the number of turns or to the mass of copper used. Thus both his Claim 2) and Claim 3) are incorrect.
Your measurements of the field are characterized by your reference to Webers as a measurement of "magnetic field intensity" instead of properly attributing it to "magnetic flux". Also, by not calculating output power, you make no attempt thus far to calculate the efficiency.
Quote from: Tom NapierFor completeness I should point out that a solenoid 18 inches in diameter requires a somewhat larger current to achieve the same magnetic field intensity as would one only 3 inches in diameter unless the length of the solenoid is increased in proportion.
Doing a final step like this is not a means of correcting errors since it is treated simply as a "cherry on the top". This is supposed to go with the rest of your calculations in a very rigorous manner.
Quote from: Tom NapierA final confirmation:
I predicted that the power needed for a given field is:
808*F*F*H*(Q + P) Watts.
-----------------
(Q - P)
I claimed that the field was 0.004949 Weber in a solenoid 10 inches high with an outside radius of 1.5 inches and an inside radius of 1 inch. The above equation gives 0.990 Watts which agrees with the figure found above for both the 500 turn and the 8000 turn solenoids.
In the second case H and P remained at 10 and 1 inches but Q became 9 inches. We calculate the power to be 0.247 Watts which also agrees with the result above. If P is made negligibly small compared to Q then the minimum power required is 0.198 Watts, not zero as predicted by Newman.
Again, and again, the field you speak of has no mention of how much potential energy is stored or how quickly it is done so.
Quote from: Tom NapierAppendix:
1] Volume of copper, V = H*pi*(Q*Q - P*P) cubic inches
2] Length of wire, L = H*pi*(Q*Q - P*P)/T*T inches
3] Resistance, R = 0.63*H*pi*(Q*Q - P*P) ohms
---------------------
T*T*T*T*1,000,000
4] Number of turns, N = H*(Q - P)/T*T
5] Field, F = 0.00004949*N*I/H Webers
You call this a formula for Webers, but this is for units of Teslas. To get Webers you have to integrate Telsas with respect to differential area. I'm not sure about the use of "0.00004949" either, which seems to stem from Maxwell's equations but appears simplified to make it understandable to college undergraduates.
Quote from: Tom Napiercombining 4] and 5] we get
6] Field, F = 0.00004949*I*(Q - P)/T*T Webers
which leads to
7] Current, I = F*T*T/0.00004949*(Q - P) Amps
8] Power = I*I*R Watts
= F*F*T*T*T*T*0.63*H*pi*(Q*Q - P*P)
-------------------------------------------------------
0.00004949*0.00004949*(Q - P)*(Q - P)*T*T*T*T*1,000,000
9] This reduces to: 808*F*F*H*(Q + P) Watts
-----------------
(Q - P)
By adding a source of bound current (i.e. permanent magnets), the value for F would increase. From there it could be maintained without any additional power. Of course, like I have said many times to myself and others, "Magnets do not do any work.! The field must change over time!"
Quote from: Tom NapierNewman -- point by point
Part 2, Commutators and coils
Prepared by Tom Napier. Copyright © 1999, All rights reserved.
Introduction:
This document is one of a series which address specific errors in the book, "The Energy Machine of Joseph Newman."
This section examines the construction of Newman's "Energy Machine" and attempts to make sense of his performance figures. It relates to the section of Newman's book which runs from page 60 to page 70. (Page numbers refer to the 8th edition.)
The early models of the Newman Energy Machine consist of a rotating magnet placed near or inside an air-cored solenoid. A commutator attached to the magnet shaft switches the current from the battery through the windings of the solenoid.
The principle of the motor is that the interaction of the field generated by the current flowing through the coil and the field of the permanent magnet causes the rotating part to make almost a half turn. By reversing the direction of the current flow at the end of the first half turn one can cause the rotor to make a second half turn. The current is then switched back to its original direction for the third half turn, and so on. The commutator and brushes act as a reversing switch to change the current direction twice per turn. This automatically causes a series of impulses which tend to turn the rotor in the same direction, resulting in continuous rotation.
This form of motor dates back to the earliest days of the electric motor. It is still used today as a laboratory demonstration or a toy, though more commonly in the form in which a coil rotates within a fixed magnet.
The advantage of using a rotating coil is 1) the moving part can be much lighter since the heavy permanent magnet is stationary and 2) fewer brushes are needed since the coil being driven rotates with the commutator and can be directly wired to it. The chief disadvantage of this simple motor is that its torque varies considerably throughout the cycle and drops to zero twice per cycle. Should a motor stop near this dead-point it will not start again without being pushed.
For these reasons practical motors are built with many more windings on the armature and hence many more commutator segments. This means that the active winding is always the one with the most torque being exerted on it. This gives both a smoother and a stronger torque characteristic for a given input current. Multi-pole motors always self-start.
One interesting feature of the motor is that it has a well defined maximum speed. As the commutator switches on the battery voltage to the coil the current starts to rise at a rate which is inversely proportional to the coil's inductance.
This is the section where you mention inductance.
Quote from: Tom NapierHowever, as the current increases the drop across the coil's resistance reduces the effective voltage and hence the rate of rise of the current. As a result the current rises more slowly as time passes and, given long enough, reaches a fixed value V/R. Normal motors have low inductance windings so the current only reaches the resistance limited value at very low motor speeds. This is why DC motors take a large current when they start or are stalled.
However, at high motor speeds a second effect takes over. The rotating magnet induces a voltage in the coil which opposes the input voltage. At a high enough motor speed this induced voltage cancels out the driving voltage and the coil current drops to zero. This is a good time to break the commutator connection. Firstly, since the coil current is zero, no large voltage spikes will be induced. Secondly, it stops the induced voltage driving a reverse current through the coil and slowing down the motor.
Newman's motor has a single stationary winding and a rotating two-pole magnet. Since he uses very big and heavy coils this makes sense. Because the coil is stationary his commutator has four brushes, two to carry the current in from the battery and two more to carry the current out to the coil. His motor has two other odd features. One is that the two halves of the commutator are not continuous, each is cut into 10 sets of three segments. During each half turn of the magnet the coil is in turn powered, unpowered and short-circuited. The other strange feature is that the coil has a much higher resistance and inductance than is commonly found in electric motors. If the concepts of resistance and inductance are unfamiliar to you see the Appendix.
This section is a very good analysis thus far.
Quote from: Tom NapierTo make a magnetic field change rapidly, as you must do to reverse the field as the rotor turns, you must either apply a very high voltage or use a low inductance coil. Newman has chosen to use a high voltage, everyone else wants motors which run from 12 volts or 110 volts so they use a lower inductance.
When you apply a voltage to a coil the current through it starts to rise.
It is also true that the density of charge in the conductor will rise with the increase in voltage. Capacitance in a wire of a given conducting substance also adds the same way as resistance. Two wires connected in series have more capacitance than two wires connected in parallel. Unlike electrical devices which contain a high capacitance per volume, wires capacitance differs by being relatively thin as opposed to flat. The capacitance is very dependent on the distribution of charges.
Quote from: Tom NapierIf neither the coil or the power source had any resistance the current would rise for as long as you applied the voltage. In practice both the supply and the coil have a considerable resistance. The rate of rise of the current, initially high, falls exponentially with time. It eventually settles down at a constant value controlled only by the total resistance and the voltage. If you cut off the voltage soon enough only the initial rise will occur.
No dispute is called for here.
Quote from: Tom NapierAppendix 1. Resistance:
All normal conductors have some resistance, that is, when current passes through them some electrical energy is converted into heat energy. Except in special cases, such as water heaters, resistance is a bad thing. When one wants simply to generate a magnetic field by passing a current through a coil of wire its resistance is a nuisance. Without it no energy would be needed to maintain the field.
That that is one of the many purposes for using permanent magnets.
Quote from: Tom NapierThe power lost to heating the wire can be calculated from I*I*R watts where I is the current in amps and R is the resistance of the wire in ohms. However, when the current is varying with time, as it is in a Newman motor, measuring or computing the total power lost becomes rather complicated.
A conventional current meter will only give the correct value for the current when the current is constant. If the current is pulsing on and off the meter is probably going to give an incorrect value. However, even if the meter does read the mean current correctly despite the pulses, this does not allow one to calculate the mean power! Because the peak power depends on the square of the current the ratio of the mean power to the mean current depends on the length and shape of the pulses.
And it depends on resistance, which in this case is variable as a result of mechanical switching! This is not a friendly scenario for someone needing testing prior to licensed certification to manfacture motors!
Quote from: Tom NapierAs a simple example, suppose 1 amp is passing continuously through a 1 ohm resistor. The mean current is 1 amp and the mean power is 1 watt. Now pulse the current so that 10 amps flows for one tenth of the time and no current flows the rest of the time. The mean current remains 1 amp. However, during the pulse the peak power is 100 watts. The other nine tenths of the time the power is zero. That is, the mean power is 10 watts. Even though the mean current is the same the input power has risen by a factor of ten. The power being dissipated in the resistor has also gone up by a factor of ten, possibly making it dangerously hot. Thus, the mean power cannot be calculated from the mean current. This, unfortunately is what Newman and Hastings do regularly.
Tough luck!
Quote from: Tom NapierAppendix 2. Inductance:
When you change the current flowing in a coil of wire you also change the magnetic field surrounding it. This changing field induces a voltage across the coil which acts against the source providing the input current. The faster the current changes the higher the voltage must be applied to make it change. The extent to which a coil resists a change in current is its inductance. Inductance is simply defined as the ratio between the rate of current input change and the voltage required to make the current change. If a coil's current increases at one amp per second when one volt is connected to it, it has an inductance of one henry.
Perfectly clear to my ear, go on.
Quote from: Tom NapierNote that a pure inductor does not limit the current. If the source could supply a constant one volt for any output current the current could increase at an amp per second for ever. All the power supplied by the source would be stored in the magnetic field. This power can be recovered when the field is reduced to zero again.
Of course in real life the resistance of the coil would limit the current to one volt divided by the coil resistance. If this was 0.1 ohms no more than 10 amps would flow into the coil and the magnetic field would stop increasing at that point. The stored energy is I*I*L/2 joules. The coil had an inductance of 1 henry so it would be storing 50 joules or enough energy to light a 1 watt bulb for 50 seconds.
Unfortunately, input energy is needed to keep the current flowing through the resistance of the coil. This energy would be I*I*R or 10 watts in this case. That is, the resistance would be wasting as much energy as the inductance has stored every five seconds. That's why inductors are not generally used to store energy except for very short periods. For example, if we tried to keep the current flowing by shorting the ends of the coil all the stored energy would be turned into heat in tens of seconds.
If you suddenly stop the current flowing, for example, by opening a switch, the magnetic field collapses very quickly. This generates a very large voltage across the ends of the coil. This voltage can be high enough to create sparks across the switch contacts. Not only is this damaging, it also wastes the energy which was stored in the coil.
Clearly so.