eye magnetic field sensitivity

Hi all,

Just a (crazy!) idea: when a rod/cone is energized by light hitting it in the eye, this will generate an electric current through the rod, and effectively make it a small electromagnet for a short time, which could allow it to be sensitive to external magnetic fields.

cheers, Jamie

Reply to
Jamie M
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On a sunny day (Mon, 17 Sep 2012 22:30:33 -0700) it happened Jamie M wrote in :

It is not strange idea, magnetic stimulation of brains cells works the same way. You can google for that. Switching on and of a large magnetic field near your head can make your arms jolt.

Reply to
Jan Panteltje

Check out rTMS, its focussed toward the brain not the eyes. Quite weird noises / scalp reaction.

Reply to
Dennis

Nerve stimulus is an electro-chemical interaction. There is no mag field that is of any significance. The photon response the rods and cones create is electro-chemical as well, and is very, VERY small. Birds do not geo-locate with their eyes, there is a different, directly brain connected region where that takes place.

There is more energy in the nerve axons repeating the data on the way to the brain region it ends up in (visual cortex) than there is in the original reception at the retinas.

Reply to
MrTallyman

Try it!

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John Larkin         Highland Technology, Inc

jlarkin at highlandtechnology dot com
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Reply to
John Larkin

Ever been in (or near) an MRI scanner? The magnetic field is probably the strongest most humans will ever experience. Put an aluminum tray in the field on edge and it takes a minute or more to lay flat. I do feel something strange when near one, so I think my magnetic sensor is affected, but nothing visual happens. (Scientists have reported a magnetic sensing organ in mammals, in or near the nose, that is sensitive to the magnetic field.)

Jon

Reply to
Jon Elson

There are "epic" photos for years on the internet of things that got too close to the MRI.

Reply to
miso

The DC field is strong, but the pulsed gradient fields are a lot weaker. I'd expect it would take a high dB/dT field to make visual effects, like discharging a cap into a coil or something.

I got my head MRId once and didn't notice anything strange.

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John Larkin         Highland Technology, Inc

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Reply to
John Larkin
[snip]

Me too. But almost had a claustrophobic panic :-( ...Jim Thompson

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| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
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Reply to
Jim Thompson

I just found it noisy and boring.

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John Larkin         Highland Technology, Inc

jlarkin at highlandtechnology dot com
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Reply to
John Larkin

Most people just notice the noise from the associated air conditioning.

Big degaussing coils and air cored mass spectrometer magnets are about the most rapid dB/dT you find in common lab experience. I trashed quite a few magnetic stripe bank cards when I worked with fast sweep high power magnets. Never noticed any interesting sensations at all being near them.

Some of the big hunky supply cables would visibly twitch as the current sweep occurred. I always wondered just how long it would be before the copper work hardens and snaps!

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Regards,
Martin Brown
Reply to
Martin Brown

I found the gradient coils to be very noisy, with weird annoying sequences.

One of my customers has a conference room with an unshielded NMR magnet in the next room, just beyond the wall. They like to make a chain of paper clips, which sticks to the wall at one end and extends out almost perpendictular for a couple of feet. Looks cool.

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John Larkin         Highland Technology, Inc

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Reply to
John Larkin

I mentally designed a circuit while it was happening. It sure helped to pass the time.

Reply to
John S

I once walked around on floor above smaller animal MRI unit. Metal bar on string sure made it move radically. Since electronic research equipment was going to be on that floor, they ended up laying down steel sheets welded together on lower half of room. I don't think I've ever encountered emf effects to my brain. The people who paid for the room construction, did not appreciate my findings. I don't think anything was done to the floor below the magnet. In that same building, it was built using aluminum sided drywall because of me finding high radiation from near tv tower. Other engineering company specified construction. It all came about when somebody could not get their telephone modem to work when near a window in clear view of tower.

Greg

Reply to
gregz

Later tests in the original building on tv interference after that station went digital, tested negative to interference in any low frequency noise, ether straight or demodulated. No Carrier buzzing.

Greg

Reply to
gregz

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As must have the machine. ;)
Reply to
John Fields

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The Alcoa aluminum plant on the Mississippi River between Iowa and ? Illinois uses electric power for their smelting [for better thermal control]. They built there and planned on having underground wiring from the nearby adjacent power production facility, but could NEVER get the leaks, or something, resolved with the underground technique, so went to HEAVY lines hanging overhead. Standing at the facility I looked out and saw the hanging lines visibly twitching almost touching each other. My host commented that that was a 'quiet' day. Often the wires hit together with such force [evidently same potential just parallel current] they crack together and sound like rifle shots. His answer to my asking wasn't that hard on the wires was, yes, they wear out about one a year and have to be replaced.

Reply to
Robert Macy

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pray the super conducting magnet doesn't quench abruptly.

Reply to
Robert Macy

I don't think I've ever encountered

The effect I get is a slight sense of disorientation, not quite to the level of dizziness, but just a feeling of being slightly off-balance. This is just from the static fringe field of the MRI magnet.

Some people report singing noises that seem to come from inside the head, and maybe visual disturbance, too, in modern MRIs. They run

14 KW of RF pulses in those! I've never been inside the MRI room with the RF on, though, but have been in the magnet bore fooling around with aluminum trays and the like.

Jon

Reply to
Jon Elson

I had a MRI after I lost sight in one eye. There was a loud roar that made it difficult to hear the operator's instructions. I had a bad headache for three days after they finished.

Reply to
Michael A. Terrell

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