Coil in wall could wirelessly power multiple electronic devices

Feb 12, 2010 By Lisa Zyga feature
As the figure shows, the overall power transfer efficiency of the wireless system can be increased by powering multiple devices simultaneously, rather than each device individually. Using more than one device increases the coupling resonance. Reprinted with permission from Kurs, et al. Copyright 2010, American Institute of Physics.

(PhysOrg.com) -- A team of MIT physicists has developed a system that can wirelessly transfer power to multiple electronic devices simultaneously with high efficiency. The system takes advantage of electromagnetic resonance coupling, and could be implemented by embedding a large copper coil in the wall or ceiling of a room. Somewhat surprisingly, the physicists found that the overall efficiency of powering multiple devices can be significantly higher than the efficiency of powering each device by itself, as long as the system is properly tuned.

Physicists André Kurs, Robert Moffatt, and Marin Soljačić of MIT have published their study on the new wireless power transfer approach in a recent issue of .

As the scientists explained, the new wireless power transfer system could satisfy mid-range applications by filling the gap between short-range inductive systems (such as wireless power mats) and long-range radiative systems, which are sensitive to obstructions, require complex tracking mechanisms, and pose safety risks.

“The main goal of our research was to show that it is possible to transfer power between a source, which could be embedded in a wall, and receivers, which could potentially be embedded in actual devices, over distances comparable to the size of a room and with efficiencies that may be good enough for many real-life applications,” Kurs told PhysOrg.com.

To demonstrate their new system, the physicists built a large self-resonant copper that resonated at an optimal frequency of 6.5 MHz. The helix-shaped coil spans an area of about one square meter, and could be embedded in the walls or ceiling of a room. The large coil, which serves as the resonant source for two smaller coils, could wirelessly transmit power to located a few meters away, although efficiency decreases with distance.

The system works on the principle of electromagnetic , in which all devices are resonating at the same frequency. When this happens, the devices can transfer energy between themselves while interacting weakly with other off-resonant objects. The researchers also showed that the cross-coupling between electronic devices is about 15 times smaller than the coupling between each device and the source coil, which is necessary for efficient power transfer.

Experimentally, the scientists showed that the system could supply more than 25 watts of power to each of two electronic devices located two meters or more from the source coil. In addition, the researchers found that powering multiple devices simultaneously could increase the overall efficiency. For example, the system could achieve power efficiencies greater than 50% for multiple devices, whereas the power efficiency for a single device was less than 20%. Having multiple devices increases the coupling resonance, which leads to greater efficiency.

“Before it is widely used, we need to embed the receivers in a seamless way into devices,” Kurz said. “We would also like to make further improvements to the performance. Perhaps someday it will find its way into many consumer applications.”

Explore further: Thermoelectric power plants could offer economically competitive renewable energy

More information: André Kurs, Robert Moffatt, and Marin Soljačić. “Simultaneous mid-range power transfer to multiple devices.” Applied Physics Letters 96, 044102 (2010). doi:10.1063/1.3284651

4 /5 (29 votes)

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User comments : 64

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TheBigYin
3.6 / 5 (5) Feb 12, 2010
I'll be sure to sleep with a tinfoil hat on.
Doug_Huffman
3 / 5 (5) Feb 12, 2010
Hah! Wait 'til the anti-cellphone EMF radiation crackpots get hold of this!
holoman
4.5 / 5 (2) Feb 12, 2010
Be able to charge my toothbrush while in the backyard.

the energy efficency is poor, energy loss into
heat into the wall.

we need a Q factor greater than one from this concept and not less than 1.

Energy is important and wasting it to make
a concept seem revolutionary isn't impressive.

SmartK8
1.5 / 5 (2) Feb 12, 2010
I hope this will be implemented soon. All the computer cables, under my table, created sort of a gordic knot over the time, and must be moved as one piece since. The distance is short, so at least in this particular case it'd be a relieve.
El_Nose
2.5 / 5 (4) Feb 12, 2010
Speaking to the gordic knot of cables Smart k8 mentioned

Why is it we have cables now anyway??? the throughput of my wireless router FAR outdoes my internet connection so why do we need to physically connect the monitor to the case?? We did away with it for key boards and mice...

Also why don't keyboards come with a super small usb device that goes unobtrusively in a usb port on the back of your computer comparible to tiny thing i get with wireless mice intended for laptops. I buy laptop mice and use them for my desktop because its cheaper and you need a battery either way,, but that way I don;t need that clucky signalling station.

I am all for this technology -- but the EM freaks are partially right we are ever increasing the amount of EM radiation we are exposed to from cell phones to radiowaves to wrieless routers in every apartment ( I can get 7 strong signals) will energy transmission push us over the edge ... I hope not
mauro48it
3 / 5 (7) Feb 12, 2010
Are you sure you wish live for the rest of your life in a low frequency owen?
Are you sure that a part of your body or a part of your appliances do not resonate on that frequency?
antialias_physorg
4.8 / 5 (6) Feb 12, 2010
Why is it we have cables now anyway??? the throughput of my wireless router FAR outdoes my internet connection so why do we need to physically connect the monitor to the case??

Because one transmit information (your router) while the other transmits power (and information depending on what your cable looks like)

I'll stick to cables when it comes to transmitting power - it's MUCH more efficient. As someone already noted: Needlessly outfitting a place with an energy wasting infrastructure is stupid when today we shgould be saving energy.

C'mon - How much effort is it really to plug in a cable? And how often do you move them once you have plugged a new appliabce in? Every blue moon.

That's not to say I couldn't envision special applications for his. But certainly not in the home.
Objectivist
3.8 / 5 (4) Feb 12, 2010
A giant coil in the wall doesn't seem very practical. Wouldn't it be better if you'd install smaller coils in tables, with a much more directed effect, to power whatever is placed on it? Such as a TV, lamp, laptop, etc. Perhaps even a big cluster of small coils inside such a table that may increase and decrease the throughput of each coil separately on demand (from the device, which the table would seemlessly communicate with via a built in positioning system). Then wherever a device is put it would create a "hotspot" with more active coils.
Quantum_Conundrum
4 / 5 (2) Feb 12, 2010
antialias_physorg:

I agree. Mostly, I think this is a stupid idea, especially in the home or even in most business or industrial applications.

There is no good reason to have electricity or other forms of energy just arcing through the air "just for the hell of it".
Skeptic_Heretic
3 / 5 (3) Feb 12, 2010
Why is it we have cables now anyway??? the throughput of my wireless router FAR outdoes my internet connection so why do we need to physically connect the monitor to the case??

For the longest time all TV was wireless. Then we decided it wasn't good enough and laid cable across the world. It wasn't until recently that wireless became both powerful enough, and safe enough for home use.

I'm a fan of the coil electricity distribution system. Too bad Tesla isn't around to see his brainchild become manifest.
Caliban
1.5 / 5 (2) Feb 12, 2010
Kind of a sidebar- but here's link to story a few days ago that seems to me like the way to go:

http://www.physor...481.html

This would make it possible to avoid all the troubling issues voiced above. The idea of all that EMR in the air where I live is disturbing.
I'll stick to cabling for now.
Quantum_Conundrum
3.7 / 5 (3) Feb 12, 2010

For the longest time all TV was wireless. Then we decided it wasn't good enough and laid cable across the world. It wasn't until recently that wireless became both powerful enough, and safe enough for home use.


Wireless antenas WEREN'T good enough, AT ALL.

Constant static and interference from EVERYTHING, and complete loss of signals from literally a cloud or a gust of wind, have to go outside and spin the antena to get it aligned right again, every day or two, etc.

Of course, the only benefit of wireless television was that you didn't pay for the service! Once you had an antena, only the advertising companies paid, and the consumer paid nothing!!

Still, I would not want my television or internet done on a wireless system unless it was at least 10 times more reliable than existing cell phones, which still suck, BTW...

CAn you imagine "static" or "snow" on an internet connection with modern internet sites? You'd never be able to do anything really...
Quantum_Conundrum
3.3 / 5 (3) Feb 12, 2010
I'm a fan of the coil electricity distribution system. Too bad Tesla isn't around to see his brainchild become manifest.


I don't think this is what Tesla had in mind.

He intended to create a system of large scale energy transfer, say from city to city, or power plant to city using wireless, but from what I've seen on the subject, I don't think he intended people to have appliance-strength energy beams bouncing around inside the home...
Skeptic_Heretic
4.8 / 5 (4) Feb 12, 2010
Still, I would not want my television or internet done on a wireless system unless it was at least 10 times more reliable than existing cell phones, which still suck, BTW...

The majority of data traffic in the world is sent wirelessly for the majority of it's transit now a days.

As I said, wireless got better. Back then it was good enough, (when compared to the cost of running cable across the planet).

Tesla's dream was completely wireless energy. In the home and outside of the home.

He insisted that the most dangerous thing about electricity was all the wiring on more than one occasion.
dirk_bruere
2 / 5 (1) Feb 12, 2010
Just wrap the coil around your house.
xstos
4.3 / 5 (4) Feb 12, 2010
can't wait to order my magneto magnetic underwear and float through my house like an x-man
tkjtkj
2.7 / 5 (3) Feb 12, 2010
It's not surprising that 'techie buffs' such as most of us are here seem to ignore any details of the physiological effects of EMR! Fortunately, the FCC is supposed to care .. there are many regulatory items already . Unfortunately, these were written/enacted years and years ago and just cant reflect the plethora of radiation sources now bathing us all.
The 'cellphone-braincancer' debate isnt even over, and that's a milliwatt issue!

I believe that this problem and the problem of toxic consequences of nanotechnologies represent the most dangerous combo we've ever imagined: (excuse me while i turn off my electric blanket ... brbbbb........

jon
tkjtkj@gmail.com
fixer
5 / 5 (3) Feb 12, 2010
Great for high density housing though, no need to put the power on or pay the bill.
Just tap everyone elses power.
Another point, YOU may choose not to have this radiation in your house, but if your neighbour has it then so do you.
A bit like second hand cigarette smoke!
Mercury_01
1.7 / 5 (3) Feb 12, 2010
Yeah, just what I want. A giant EM coil in my house thats connected to the new smart grid. Oh, and sure Mr census man, go ahead and record the exact GPS coordinates of my home. Im a good citizen. I have nothing to hide, and why would anyone on earth want to cause me any ill?
http://www.satweapons.com/ -click "more information"
antialias_physorg
5 / 5 (6) Feb 12, 2010
There's a bit of a misunterstanding here:

We're not talking about wireless INFORMATION transmission (which requires very low power and is biologically (probably) of no importance).

The article, however, talks about wireless POWER transmission. We are talking about sizeable amounts of energy here (orders of magnitude larger than used for information transmission!).

Even in the days of antenna-TV the TV was plugged in to get POWER. No way could the antenna signal power a TV set.

Transmitting power like this in your home engenders a bit of a questionmark when it comes to biological effects.
Ulg
4.7 / 5 (3) Feb 12, 2010
I'm a fan of the coil electricity distribution system. Too bad Tesla isn't around to see his brainchild become manifest.


I don't think he intended people to have appliance-strength energy beams bouncing around inside the home...


His attempts to globalize electricity through the atmosphere was different- he was going to use the upper atmosphere as an actual conductor (low pressure atmosphere is highly conductive) If you are talking about Wardenclyffe tower anyway.

But he also did work on portable wireless/batteryless power devices:

"I mean the transmission of power to any distance without the use of wires" - Tesla 1893 Ben Franklin Institute

There is a famous picture of his from the cover of Electrical Experimenter 1919, he is sitting in a chair holding a light bulb that is wireless and without any type of battery, he not only had his house, but a large field in the back where you could bring any of combination of his devices and they would work.
mosahlah
4.8 / 5 (4) Feb 12, 2010
If this is capable of powering my electric lawn mower, I'd be concerned. However, we are already close to the threshold of being able to power many electronics off of ambient EM radiation. It would seem to be a step forward if we could bridge the gap with a supplemental source of energy. The benefit could be a revolution in energy saving technology if we can adapt common electronic applicances such as cell phone, clocks, computers, security systems, lamps, etc. to operate at milliwatts without the need for disposable batteries, wasteful transformers and heavy grids.
Mercury_01
5 / 5 (1) Feb 12, 2010
There's a bit of a misunterstanding here:
We're not talking about wireless INFORMATION transmission (which requires very low power and is biologically (probably) of no importance).
The article, however, talks about wireless POWER transmission. We are talking about sizeable amounts of energy here (orders of magnitude larger than used for information transmission!).
Even in the days of antenna-TV the TV was plugged in to get POWER. No way could the antenna signal power a TV set.
Transmitting power like this in your home engenders a bit of a questionmark when it comes to biological effects.

Power transmission wires, or coils, can do more than transmit power. Any type of wave can be made to act as a carrier wave for other frequencies. ELFs in particular. http://www.raven1.net/elf.htm
zekesphysorg
5 / 5 (4) Feb 12, 2010
Antialias wrote:

C'mon - How much effort is it really to plug in a cable? And how often do you move them once you have plugged a new appliabce in? Every blue moon.

You seem to be forgetting the reason why you have spent your whole life only moving appliances "once in a blue moon".....it was because they had cords! We've been limited by cords and proximity to outlets all our lives, of course we aren't going to move things often.

I can't wait for the day when cords are obsolete, and I can put any appliance, computer, or gadget anywhere in my house and it...just...works.
Bob_Kob
3.4 / 5 (5) Feb 13, 2010
This is not using electromagnetic waves, its using magnetic induction. And from all knowledge, magnetic fields do not interact negatively with the human body despite its energy level.
mauro48it
5 / 5 (2) Feb 13, 2010
Some small additional doubts. Perhaps this grandiosity seems exaggerated. How to solve the problem to charge the cost of energy used in a great condominium? I do not think it is easy to confine the magnetic field within a single apartment. If someone comes who underwent surgery with sensitive electronic equipment plant? If in the apartment there is a large structure that is equivalent to a resistive coil, how much energy could absorb? It seems that the application of this principle could be much less straightforward than assumed.
Bob_Kob
4.7 / 5 (3) Feb 13, 2010
One assumes you don't have a huge sheet of metal at resonant frequency in your average home.
Ant
1 / 5 (4) Feb 13, 2010
you could call this a cancer initiator, rather like living near power transmission overhead cables
Bob_Kob
5 / 5 (3) Feb 13, 2010
Again magnetic fields don't harm humans. Look at MRIs, they operate at many times the teslas that this device would be able to produce.
Quantum_Conundrum
3 / 5 (2) Feb 13, 2010
One assumes you don't have a huge sheet of metal at resonant frequency in your average home.


You're joking right?

The "average home" has huge amounts of metals, including, usually, a metal sheet behind the oven and microwave ovens.

Let's see, there's foundation wiring and re-bar, there's the nails and staples througout the house, as well as the hurricane straps, and don't forget the copper plumbing and the faucets.

It was already mentioned, but medical implants would be endangered, and anyone with metallic fillings, implants, or braces in their teeth would be endangered, particularly in cases where they have more than one type of metal fillings.

Additionally, and MRI scan lasts for a few minutes, while exposure to coil power would last a life time.
rethinker
1 / 5 (1) Feb 13, 2010

I think a coil in every apartment wall may be just what people want,or need, or don't need.

When the baby crib is near the coil and it can send power to his or her auto bottle feed, that makes it so we wont have to go into the room and manually do it. More time for TV.
seneca
2 / 5 (2) Feb 13, 2010
I'll be sure to sleep with a tinfoil hat on.

This technology was proposed by freaky Tesla before many years, but it was controversial from its very beginning - not only with respect to its apparent inefficiency, interference with another electronic devices (it could destroy your computer of wifi tower easily at distance) and negligible impact to human health.

For example, high intensity of high frequency field could cause uncontrolled formation of electric sparks between conductive objects, whenever they appear at proximity accidentally. It means, you should invest into your fire pull alarms well, if you're planning to change your bedroom into microwave oven.
seneca
3.7 / 5 (3) Feb 13, 2010
Again magnetic fields don't harm humans. Look at MRIs, they operate at many times the teslas that this device would be able to produce.

Steady state magnetic field (like those in MRIs) cannot transfer energy at distance - no matter how intensive it could be. Stop watching TV and learn some physics.
seneca
2.3 / 5 (3) Feb 13, 2010
Even electromagnetic waves of radiofrequency range could be unpredictable and dangerous. In 2007 retired radio-engineer John Kanzius developed an apparatus for cancer treatment by polarized radiowaves in 13 MHz frequency range (which is pretty close to 6 MHz, used in the disputed article).

During desalination tests of his device with tube filled by marine watter (~ 3% solution of NaCl, very close to concentration of salt in body fluids) he observed an evolution of hydrogen peroxide and gaseous hydrogen, which can be ignited by lighter (video http://tinyurl.com/yjr8dlw ). Experiments were confirmed and replicated by material scientists at Pennsylvania State University.

http://tinyurl.com/l3flvv

Do you want to evolve hydrogen and peroxide in your bedroom, while sleeping or listening music? Frankly, me not...
seneca
3 / 5 (2) Feb 13, 2010
..All the computer cables, under my table, created sort of a gordic knot over the time, and must be moved as one piece since...
You'll save only one cable from this knot - the power line one. The other cables will just become thicker due the need of better shielding. In addition, you'll need a much complex & better power sources in your computer & other electronic devices, capable of handling changes in input power. It's not so easy and simple, how it appears at the first look.
otto1923
3.3 / 5 (3) Feb 13, 2010
increasing the amount of EM radiation we are exposed to from cell phones to radiowaves to wrieless routers in every apartment
Which is inevitable and unavoidable, and will only increase as we look to implant telemetry and 'telepathic' communication via embedded devices. I suppose 'natural' selection would begin to adapt the species but treatments will be devised until favorable genetics can be identifed and the general population re-engineered to compensate. Artificial EM is now a permanent part of the human condition.
Mercury_01
5 / 5 (2) Feb 13, 2010
Again magnetic fields don't harm humans. Look at MRIs, they operate at many times the teslas that this device would be able to produce.


What makes you think that? Moving EM fields have been proven to induce mental states in test subjects. I thought that was common knowledge. this device operates at 6.5 Mhz. What would stop someone from sending 7.8 Hz ELF waves into our homes, ridden on the guise of a Mhz carrier wave? We would be oblivious. glued to our TVs and drooling in a highly suggestible theta state.

And dont say its not a wave. Induction IMPLIES that the field from the coil is moving at a given rate.
Bob_Kob
3 / 5 (1) Feb 13, 2010
Hmm that is disconcerting. I was always under the impression that magnetic fields, even if alternating did not interact with our molecules with any dramatic effect.
JacobA
2.3 / 5 (3) Feb 14, 2010
This technology seems quite practical in a sense but it also seems very dangerous. I know this type of technology has been around for a long time. I was under the impression that it didn't catch because sending high amounts of energy around could destroy DNA structure and cause cancer and tumors.

Speaking from experience I know of way too many people who are either fighting or have died from cancer. The last thing we need is to turn our living room into a microwave oven because we can't be bothered to plug in a chord. I really hope this does not become common place in the home or any residential area. Also, it seems like a gross waste of energy seeing as most of the energy would be lost to ambience.

I am only a layman not a physicist so correct me if I am wrong.
Skeptic_Heretic
5 / 5 (1) Feb 14, 2010
I am only a layman not a physicist so correct me if I am wrong.
It's a matter of whether we're talking ionizing energy or energy of a significant amount of force required to "remove" pieces of DNA.

If we can use energy more efficiently then the broadcast strength need not be much.

Think of lighting. You can briefly illuminate a CFL by dragging your feet on a shag carpet. Energies at that level are hardly deleterious, unless you're highly suceptible to static shock induced death.
antialias_physorg
5 / 5 (1) Feb 14, 2010
Again magnetic fields don't harm humans. Look at MRIs, they operate at many times the teslas that this device would be able to produce.


1) MRIs work with a static field (the variable field used for reading the signal is much lower powered). A static field does not induce any electrical current in a conductor (unless you move the conductor which you don't in an MRI)

2) You don't live 24/7 in an MRI

The propsed system would bathe you constantly in a shifting magnetic field. The body is not a perfect insulator so you'd constantly have low powered currents induced in your body.

Now I don't know about you, but I don't think our bodies were designed for this (and anything they weren't designed for tends to have harmful side effects if it is experienced for too long)

Additionally you would have to ban all passive metal objects from your appartment since they would constantly draw power.
Mercury_01
4 / 5 (1) Feb 14, 2010
Hmm that is disconcerting. I was always under the impression that magnetic fields, even if alternating did not interact with our molecules with any dramatic effect.


Im not too sure about DNA and cancer risks, Im just speaking of the effect certain waves can have on electrical brain activity.
RETT
5 / 5 (1) Feb 15, 2010
An MRI is a pulsed magnetic field in a superconducting coil. It is the pulses that produce the image slice. In any case, a magnetic field from anything other than a permanent magnet is also pulsing continuously, which is the only way that it can induce current flow in anything. Permanent magnet motors must still have induced variable fields to create motion. This may be by mechanical motion, but it is still variable. In the case of these charging coils, we are hoping that a very high percentage of the energy is transferred at the resonant frequencies and that other formations that can resonate do not extract the energy by "accident". This would be your pacemaker or the pen or keys in your pocket, or maybe even your cell phone that was not designed to charge itself this way. This whole idea sounds completely half-baked as could be the humans exposed to the wrong type of resonance. I think that I and most sensible people will pass.
seneca
5 / 5 (2) Feb 15, 2010
Im not too sure about DNA and cancer risks

DNA disintegrates in electromagnetic field, but the required frequencies reported are somewhat higher..

http://arxiv.org/abs/0910.5294

Of course, if salt water can be electrolyzed in 12 MHz field, then one could be never sure by anything...

http://tinyurl.com/yjr8dlw

We simply need more experiments in this area - it seems for me, most of physicists are pursuing Higgs bosons and black holes at LHC and no one cares about boundary phenomena of classical physics.
seneca
3 / 5 (3) Feb 15, 2010
It seems, microwaved watter isn't very healthy for some plants..

http://www.intern...rch.html
Mercury_01
3 / 5 (2) Feb 15, 2010
Well, yes, obviously higher frequencies mike microwaves can damage our biology.
It seems, microwaved water isn't very healthy for some plants..

http://www.intern...rch.html

Yeah, I havent used a microwave in 5 years for that reason (also, having one just promotes unhealthy eating). Someone needs to do a large scale experiment with that.

Water's weak bonds form a type of lattice in the liquid state that plays a role in biology. In fact, our cytoplasm is polarized in a manner that facilitates the movement of cellular mechanisms.

Consider this: The very first cells arranged themselves into spheres by way of polar attraction and repulsion.

Our biology rests on electrical activity. Its obvious that we need more studies before we let some enterprising geeks bring this 100 year old resonance experiment into our homes.
fixer
5 / 5 (1) Feb 15, 2010
An entire medical industry is based on the interaction of magnetic fields and the human body.
Unless you are prepared to denounce this industry as fraud write this article off as a "techie" joke.
Let's move on to something sensible.
antialias_physorg
5 / 5 (1) Feb 15, 2010
An entire medical industry is based on the interaction of magnetic fields and the human body.


Have you ever seen any of these applications in the hospital (besides MRI)? No. Me neither.

These 'magnetic healers' _are_ a fraud. There are no studies to support them and your medical insurance certinaly on't cover them.
fixer
4 / 5 (1) Feb 16, 2010
They may be a fraud, but it is proven that a magnetic coil will polarise iron in the blood.
Incidently, cancer contains a lot of iron and an inductive field is used to cook it in situ, so I wouldn't be too quick to dismiss it all as fraud.
Skeptic_Heretic
3 / 5 (4) Feb 16, 2010
Have you ever seen any of these applications in the hospital (besides MRI)? No. Me neither.

PET scanners, Full body scanners, Bariatric imaging is done via magnetic resonance.

We use EM fields for almost 80% of non-physical diagnostics and it's involved in 3% of treatments, (mostly for cancer).
to_be_2718281828459
4 / 5 (2) Feb 16, 2010
And can you imagine a Vacuum cleaner using these coils? Damn, that would be so sweet. The biggest problem a Roomba has is it's battery life, this would get around that!

If an entire house where wired with the coils, then an 'active' room could resonate with an 'inactive' room with no current, that might get around the need for many devices active at once to create a resonance!

Resonance happens almost everywhere you go, but you're never aware of it, because we don't have the needed sensory organs, which is why no one understand electric currents are not a all like water, even if we call it a "current".

At the moment, if my cell phone rings, my headset will resonate with it. Both have small coils, so when one emits, the other can receive that frequency, and I get static, the other is ready to catch it. So even with my headphones, I can hear my cell. Electricity is not like water, at all.
seneca
5 / 5 (2) Feb 16, 2010
Roomba has is it's battery life, this would get around that
Not quite, resonant coupling mechanism proposed in wireless power requires, both source, both charged object should remain at rest in well tuned distance, or the efficiency falls down. Such device could be powered by directed microwave or IR beam from floor reflector (a quite viable technology, in fact) And Roomba is able to clean whole room during single charging cycle.
antialias_physorg
5 / 5 (1) Feb 16, 2010
PET scanners, Full body scanners, Bariatric imaging is done via magnetic resonance.


PET = Positron Emission Scan. This is a scan that uses beta decay of an introduced substance (no magnetic fields are involved, though many scanners are delieverd today as double systems with MRI)

Full body scanner - this is either an MRI (which I already mentioned) or a CT (which does not use magnetic fields)

Bariatric imaging - I don't know what you mean here. Bariatric surgery is a discipline that deals with surgical applications in relation to obesity. Postoperative imaging is sometimes done via MRI.

You are right, however: There is a tratment application for cancer using magentic fields. But that treatment does not use the effect of the magnetic field on the patient. The EM field heats up a specific substance that bonds to cancer cells (basically a substance that contains metal and the EM waves are short circuited via the metal - creating a heat locus that denaturates the proteins)
to_be_2718281828459
5 / 5 (1) Feb 16, 2010
And Roomba is able to clean whole room during single charging cycle.


How dare you presume the size of my room!!!

But I'm sure there are many places where large cabling can be removed for an important advantage.

And if my radio can tune to a radio station as I walk, why not this? What we would get is a fluctuating in the power of the moving device, which means the emitter has to lower/raise whatever it's doing to match that.

It means two vacuum cleaners, moving randomly in a room, on a fixed x-y plan, with a resonant emitter somewhere, have to receive constant power in any position they may go to. I can see how that would be tricky...

But that's where the magic of batteries come in: we don't need the electric field to be constantly resonating in the devices, as long as our batteries get charged sometimes! =)
seneca
5 / 5 (2) Feb 16, 2010
And if my radio can tune to a radio station as I walk, why not this?
I'm sure, whenever such technology appears in the market, many people like you will buy it just from curiosity reasons...;-) In radio broadcasting the efficiency of energy transmission is of low significance, because signal is amplified in three to four orders of magnitude range and radio-signal becomes quite homogeneous at sufficient distance from transmitter.

Nevertheless it brings an idea of self-tuned coupling by using of varicaps or transducers in circuit, which could improve the effective range of wireless power technology. Of course such circuit could work only for single coupled pair charged.
to_be_2718281828459
4 / 5 (1) Feb 16, 2010
Buy it? I wanna try and help create it!

If I could only figure out Coulomb's law so that the Biot-Savard law is obvious in such situations.

What really surprises is how the efficiency falls off in a 1/r fashion with distance, instead of 1/r^2, the way you expect charge over distance to behave. I wonder why?

Oh, intro to electrodynamics, why must you hurt so good?
broglia
5 / 5 (2) Feb 17, 2010
... the efficiency falls off in a 1/r fashion with distance, instead of 1/r^2...
From where did you got such information? Such dependence is extremelly nonlinear due the inductive coupling. It's evident, at low distance, comparable to diameter of Helmholtz coil the efficiency of energy transfer is inductive and it doesn't depend on distance too much, whereas at the larger distance is radiative by inverse square law.

http://www.wirele...ure2.jpg
Javinator
not rated yet Feb 18, 2010
It seems, microwaved watter isn't very healthy for some plants..

http://www.intern...rch.html


Microwaves make water molecules move around. It's the movement of the molecules that makes them hot. These moving water molecules impart energy into neighbouring "food" molecules which makes them hot. It cooks things faster because the microwaves penetrate the food and move the water molecules throughout a substance more evenly than a conventional oven.

Conventional ovens/stovetops heat from the outside in or heat from the element on the stove. The heat causes the molecules on the outside to "shake" and bounce into its neighbouring water molecules and "food" molecules. And so heat is propagated throughout the food.

The water molecules aren't altered, they're simply "moved" in different ways.

There are just as many sources debunking this toxic microwaved water claim there are proving it out there.
Javinator
not rated yet Feb 18, 2010
Nice source by the way:

From http://www.intern...rch.html :

"Dr. Emoto and his team study water from different sources of the world and also water that was effected by music, image, television, thoughts of a single person and a group of people, prayers, words typed or pronounced in different languages etc. Emoto discovered that there was a significant difference between crystals that listened to Beethoven and heavy-metal. Words "angel" and "devil" form structures that are similar and completely opposite at the same time."
Skeptic_Heretic
5 / 5 (1) Feb 18, 2010
This is the best part:
Words "angel" and "devil" form structures that are similar and completely opposite at the same time."


Because water naturally speaks english.
Mercury_01
1 / 5 (2) Feb 19, 2010
This is the best part:
Words "angel" and "devil" form structures that are similar and completely opposite at the same time."


Because water naturally speaks english.

typical "skeptic" straw man logic. Its not language, smart guy, its large scale entanglement. prove me wrong, then talk like you know everything.
Skeptic_Heretic
3 / 5 (2) Feb 19, 2010
typical "skeptic" straw man logic. Its not language, smart guy, its large scale entanglement. prove me wrong, then talk like you know everything.

Distant intention is not entanglement.

Distant intention would be if I thought about killing you and my thoughts killed you.

Thinking about water does not make water do things, what sort of pseudo scientific garbage are you reading?
The Institute of Noetic Sciences conducted a double-blind test of the effects of distant intention on water crystal formation. This was done with Dr. Masaru Emoto and the participants of the International Water Festival in Tokyo, Japan sending blessings of love and gratitude to water in a remote location.
That type.
Mercury_01
not rated yet Feb 23, 2010

What makes you think you know anything about it? Got any first hand experience? Read any good books on large scale entanglement? There are none, so keep your thoughts to yourself on matters in which you have NO experience.

"Distant intention is not entanglement."

Just because you say something doesnt make it real. Hundreds of well conducted studies, all with a statistical significance greater than p.o5 speak to a different story. Your skepticism is of the NON- SCIENTIFIC variety.

Causation between seemingly unrelated events, when consciousness is an intentional factor, consistently displays a significant level of system continuity. If people like you weren't so damned PHOBIC, we could already have a full functioning hypothesis, but for those of us in the know, it's already fully apparent that consciousness is capable of large scale system entanglement, affecting at least a few properties of matter.

John_Doe
1 / 5 (1) Mar 06, 2010
"the overall efficiency of powering multiple devices can be significantly higher than the efficiency of powering each device by itself"

Guess what, the efficiency of creating brain tumors is going to be higher too.

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