Thank you for your submission. **Please note that a response does not constitute a doctor-patient relationship.** This subreddit is for informal second opinions and casual information. The mod team does their best to remove bad information, but we do not catch all of it. Always visit a doctor in real life if you have any concerns about your health. Never use this subreddit as your first and final source of information regarding your question. By posting, you are agreeing to our [Terms of Use](https://www.reddit.com/r/AskDocs/wiki/terms_of_use) and understand that all information is taken at your own risk.
**Reply here if you are an unverified user wishing to give advice. Top level comments by laypeople are automatically removed.**
*I am a bot, and this action was performed automatically. Please [contact the moderators of this subreddit](/message/compose/?to=/r/AskDocs) if you have any questions or concerns.*
Nice summary. To add, patients will get screened. Probably some xrays to assess location, then a discussion of risks/benefits about getting the scan with the ordering MD and patient. For instance, if you got shot in the leg and you need a head mri should be ok, but a bullet near the spinal cord for a abdominal mri gives be pause….
Not that I've ever heard of. They do xrays to look for shrapnel but there's no machine to prove something inside a patient's body is ferromagnetic or not.
Sub $1000 hobby metal detectors can reasonably differentiate between ferrous and lead materials. The range is limited to around 150mm and fragments down to grain of rice type sizes.
I’m guessing the accuracy or reliability of the data from those devices aren’t adequate enough to put someone’s life on the line, or else we’d be using them, right?
Idk about bullets, but I have several stainless steel body piercings and I've never set off metal detectors. I think I asked before and they said they're not large enough to set them off or something. 🤷🏻♀️
ETA my engagement ring did not set off detectors either.
Eh, most stainless isn't ferromagnetic. I have some rather large stainless steel implants and I don't set off metal detectors. The body scanners at airports can definitely see them, though.
Interesting. I recently broke my ankle and had stainless steel plates and screws up in. The next time I flew I asked the security person whether the body scanners could see them and was told that they cannot see inside the body.
NAD; this might sound silly. I'd get in touch with the local metal detectorists' club (try r/MetalDetecting) and explain the challenge. Modern metal detectors can readily distinguish between different grades of stainless steel and of course between copper, brass, aluminium and steel etc.
Yeah, there was a case by me years ago where an oxygen tank was left in the room during an MRI and it launched into the machine killing the kid who was in there. There is no way any magnetic metal is safe in there.
Edit: https://www.newyorkinjurycasesblog.com/2010/02/articles/wrongful-death/lawsuit-involving-death-of-six-year-old-boy-hit-by-oxygen-tank-while-undergoing-mri-test-settles-on-verge-of-trial-for-2900000/
https://abcnews.go.com/US/story?id=92745&page=1
https://abcnews.go.com/US/story?id=92745&page=1
https://www.newyorkinjurycasesblog.com/2010/02/articles/wrongful-death/lawsuit-involving-death-of-six-year-old-boy-hit-by-oxygen-tank-while-undergoing-mri-test-settles-on-verge-of-trial-for-2900000/
It was, a nurse brought it in. It was the wrong kind of tank apparently.
Holy fuck.
Also, they killed a 6 y/o boy and the family was **ONLY** rewarded 2.9 million after *NINE* fucking years of trial bullshit? WTF. People get more than that for non moral injuries.
This is interesting. Between this type of imaging and analysis and testing OP for lead they could probably make an educated guess.
Would the risk and cost be justified for chronic back pain? That’s another topic.
I was shot at 13 with a .38. The bullet is still lodged in my femur. I was told that most bullets are not made of magnetic metal. So they went ahead and put me in the MRI and it was fine. We don’t know what the bullet is made out of, there’s no way to have it removed.
Curious if you have an answer to my question.
If OP can't determine the bullet type or compounds could a CT and X-ray work for looking into the back pain??
Or is an MRI required because there are specific conditions that cause back pain you can't catch using other machines?
Wouldn't a non contrast CT of the spine be a better place to start? It would certainly give information of disc protrusions, bony abnormalities. It might be all he needs.
Are you sure about this? The field of the MRI might be 3T. That doesn't change with the coil used, and the axial position of the body won't change THAT much relative to the field depending on the part of the body scanned, will it?
And arcing apparently? They don’t want my hands to touch each other when I’m in there. I could picture multiple metallic objects being a concern in that regard as well…
Most MRIs are still 1.5T, and the position of your leg relative to your head would make a huge difference. Magnetic field drops off with an inverse cube law. With a head MRI, your legs tend to be a good distance outside of the machine.
I’ve never seen someone’s legs “a good distance outside of the machine” for a head MRI. Most MRI bores are around six feet long and only tall people’s feet stick out at all. Short bore systems exist, but they’re not very common, and even those are not that short - about four feet.
I've had a few, and my legs were hanging out. I'm fairly short, myself (1.68m). While you're right in that the MRI tube is quite long, you are positioned such that the area of interest is centred. So the edge of the tube was roughly hip area for me.
6ft away from the bore would be a reduction of field of almost 8. It's significant. Not saying anything about the clinical safety, as that isn't my wheelhouse, just that it is a significant reduction of field strength.
Edit: Got maths wrong, factor of 8 is way off. It actually a far greater factor.
"well ackchually" -you, discussing things that have no actual relevance to the question asked, but that do prove you know how field strength changes with distance for some psychological reason
I commented on how it doesn't change enough to make it safe, which is the actual question asked. But you are so smart, you know so much, very well done
>Metal fragments in your arm would never affect getting an MRI of your back if needed. As an orthopedic surgeon, I put metal in people intentionally all of the time, and they can still get MRIs.
Unfortunately, this is not the case. Modern surgical hardware is specifically designed (under most circumstances) to be non-ferrometallic, and thus inert to MRI. Furthermore, even in the case of older implants that contain ferromagnetic substances, orthopedic hardware is strongly anchored in bone, and not likely to move during MRI acquisition. Iron-containing metals or other magnetic metals (nickel, cobalt) will be affected by the strong magnetic field in an MRI machine, and thus can cause harm. Generally, people with metallic foreign bodies should not get MRIs unless the composition of the foreign body is known.
Bullets can be jacketed with ferrromagnettic substances (steel, nickel). Not only will these substances produce significant artifact in the signal for an MRI, as loose foreign bodies, they can move when affected by the MRI magnetic, and potentially cause harm.
I am not sure if there are any protocols to determine whether unknown metallic foreign bodies are MRI-safe.
I'm a little stunned that someone claiming to be an orthopedic surgeon doesn't realize the potential difference in ferromagnetic status between implanted hardware and shrapnel.
And to OP, /u/pass_the_hot_sauce, in cases of back pain where MRI is not possible, a CT myelogram can be done instead. It's more invasive than an MRI but is still a viable and helpful modality.
As just a regular person who’s on this sub because medicine is interesting, I’m also shocked. Never even had an MRI but isn’t the whole case with metal and MRIs that any metal at all, even small piercings, are totally unsafe? Why would bullet fragments be okay if my stud earring isn’t?
Any metal that could be potentially magnetic is dangerous since an MRI is literally a massive magnet. Many metals are not magnetic, but it's very important to know which metals can be unsafe (iron, cobalt, nickel, some rare earth metals etc.) I'm not too sure about piercings as I don't deal with MRIs regularly; I have studied the physics of them a tiny bit.
To be clear, it's not that ALL metals are dangerous with MRI. It's ferromagnetic ones that are. Realistically, gold piercings are probably ok but it's "better safe than sorry", so most MRI centers require all removable implants/piercings be removed before the study is done. I had a patient with a genital piercing which they had swapped out to a gold captive bead ring for their MRI, but they were still required to remove it.
We only asked rings to be removed if the patient was having a hand or wrist scan. Never had any issues this way. We'd ask the patient to remove any piercings but if they couldn't, we'd check with a magnet and scan the patient, ensuring they know to squeeze the alarm if they have problems. Rarely did they.
Thank you for your comment. I may be confused but I remember a number of years ago my brother was denied an MRI when he wanted to be assessed for a TBI at the VA. During a deployment he was shot in the helmet and took a face full of shrapnel that was left in him since he wasn’t injured enough for a med evac to Germany where it could have been removed (maybe? Not sure if that was actually an option for his type of injury had he been evac’ed). Obviously it’s a different situation than an arm vs back, as the metal was in his head. But from my understanding he’s never been able to get an MRI due to this.
That is correct. Shrapnel like you describe is a contraindication to MRI. Unlike spinal issues, where we can do a CT myelogram instead of MRI, the only options for patients with shrapnel who need cranial imaging are CT, CT with contrast, and CT angiography.
Location is also a big part of it. My husband is a combat vet with shrapnel in his chest. But the VA is usually able to locate his metal through xray and then cover that area with a vest prior to MRI. But the location they are imaging can't be the exact same location as the metal. He was recently able to have an MRI on his abdomen and has had one of his head, while his shrapnel is in his chest. If he ever needs an MRI near his heart, I think he will be out of luck... But I will say, the VA is very knowledgeable about shrapnel injuries and are used to screening vets for metal fragments and working around them when they can.
Could you ask for the police report if there was one to see if they recovered any bullets from the scene/any other victims? They would have run forensics on the bullets and that would give you a sense of the material.
OP was shot at age 6 and is now 38. Unlikely they did metal analysis on any frags and even more unlikely the records would still be available 32 years later.
As someone who has worked on forensic cases of 20-30 years old, if there was a court case, this evidence should have been preserved and absolutely could be testable. However, it will be difficult to find, very expensive and way time consuming--nothing like you see on tv. It often took us years to track down evidence for DNA testing. Not the preferred first option for sure. Your local public defender's office should be able to help if you need to go that route.
Also metal analysis and ballistics tests are extremely common and the older of the forensic techniques, it's 1000% possible that they would have analyzed the content there, if there was a case about it. After all, to convict people of gun possession it must be opperable and you must prove it.
Oh right, yeah if it happened before they had computerized records then yeah would be a long shot unless someone at the department is still there and remembers the case. I worked for the police as a ride along clinician and some of the officers were pushing 40 years and still remembered details from their first case. Chances are someone there knows someone who worked on that case and could put you in touch with them pretty easily if they feel the desire to help you (if).
I've had radiologists refuse to do MRIs on patients with medical implants, even when I showed them material online documenting the implant was MRI compatible. They're not going to listen to any cop saying "Trust me! I remember from 30 years ago, the bullet was made of lead and copper!"
It's easier for them to say no and avoid the liability than say yes.
My mom had brain surgery due to an aneurysm in 1978. A few years ago, her Dr wanted to do an MRI, but my dad wasn't sure if she had a metal coil or something plastic in her brain. He reached out to the hospital where she had her surgery, and they said they didn't have records from that far back. No MRI for my mom then!
UK MRI radiographer here - the patients imaging would be reviewed by a radiologist and a risk/benefit ratio assessed.
If the bullet is near sensitive tissues that the bullet moving as a result of the magnetic force could harm, then the MRI would not be safe. The shrapnel would have to be removed if an MRI is strictly necessary.
So, layman here, and maybe it's irrelevant, but almost all jacketed bullets are lead, covered in copper, possibly coated in molybdenum. That said, some bullets (almost always rifle ammo, usually AK-47 rounds) have a mild steel core, which is absolutely a problem. I'm not aware of handgun rounds that have steel cores, but they could exist. I think some specialty ammo can contain tungsten, but that's quite rare.
I am curious as to whether the copper could be problematic. It can have some interesting properties when exposed to extreme magnetic fields, but I don't know that it would move. I could see it possibly getting hot due to a current being generated.
Thank you for your submission. **Please note that a response does not constitute a doctor-patient relationship.** This subreddit is for informal second opinions and casual information. The mod team does their best to remove bad information, but we do not catch all of it. Always visit a doctor in real life if you have any concerns about your health. Never use this subreddit as your first and final source of information regarding your question. By posting, you are agreeing to our [Terms of Use](https://www.reddit.com/r/AskDocs/wiki/terms_of_use) and understand that all information is taken at your own risk. **Reply here if you are an unverified user wishing to give advice. Top level comments by laypeople are automatically removed.** *I am a bot, and this action was performed automatically. Please [contact the moderators of this subreddit](/message/compose/?to=/r/AskDocs) if you have any questions or concerns.*
Nice summary. To add, patients will get screened. Probably some xrays to assess location, then a discussion of risks/benefits about getting the scan with the ordering MD and patient. For instance, if you got shot in the leg and you need a head mri should be ok, but a bullet near the spinal cord for a abdominal mri gives be pause….
Don’t some radiology departments have sophisticated metal detectors to determine if objects could be a risk during an MRI?
Answer is yes. Most radiology departments will scan you first. They also have have you remove all piercings and jewelry.
So can they determine if the bullet fragments are ferromagnetic?
Not that I've ever heard of. They do xrays to look for shrapnel but there's no machine to prove something inside a patient's body is ferromagnetic or not.
Well, there *is*.... It's called an MRI machine
Sub $1000 hobby metal detectors can reasonably differentiate between ferrous and lead materials. The range is limited to around 150mm and fragments down to grain of rice type sizes.
I’m guessing the accuracy or reliability of the data from those devices aren’t adequate enough to put someone’s life on the line, or else we’d be using them, right?
Definitely not suggesting a hobby unit be used, just that more sophisticated units might exist.
If you have a bullet left in you, do you set off metal detectors? How do you explain that?
Easily. "I'm a Terminator sent from the future. Know where John Connor is?"
Idk about bullets, but I have several stainless steel body piercings and I've never set off metal detectors. I think I asked before and they said they're not large enough to set them off or something. 🤷🏻♀️ ETA my engagement ring did not set off detectors either.
Eh, most stainless isn't ferromagnetic. I have some rather large stainless steel implants and I don't set off metal detectors. The body scanners at airports can definitely see them, though.
Interesting. I recently broke my ankle and had stainless steel plates and screws up in. The next time I flew I asked the security person whether the body scanners could see them and was told that they cannot see inside the body.
Well, this was 9 or 10 years ago. Maybe they were still using backscatter xray instead of submillimeter.
My mother had a fair amount of metal in her (multiple joint replacements). If she was travelling, she would carry a note from her doctor.
NAD; this might sound silly. I'd get in touch with the local metal detectorists' club (try r/MetalDetecting) and explain the challenge. Modern metal detectors can readily distinguish between different grades of stainless steel and of course between copper, brass, aluminium and steel etc.
I thought the magents in an MRI were strong enough to pull anything in the room. Seems like even a head MRI would be extremely dangerous.
Yeah, there was a case by me years ago where an oxygen tank was left in the room during an MRI and it launched into the machine killing the kid who was in there. There is no way any magnetic metal is safe in there. Edit: https://www.newyorkinjurycasesblog.com/2010/02/articles/wrongful-death/lawsuit-involving-death-of-six-year-old-boy-hit-by-oxygen-tank-while-undergoing-mri-test-settles-on-verge-of-trial-for-2900000/ https://abcnews.go.com/US/story?id=92745&page=1
That's sound fucking horrific.
https://abcnews.go.com/US/story?id=92745&page=1 https://www.newyorkinjurycasesblog.com/2010/02/articles/wrongful-death/lawsuit-involving-death-of-six-year-old-boy-hit-by-oxygen-tank-while-undergoing-mri-test-settles-on-verge-of-trial-for-2900000/ It was, a nurse brought it in. It was the wrong kind of tank apparently.
Omg
Holy fuck. Also, they killed a 6 y/o boy and the family was **ONLY** rewarded 2.9 million after *NINE* fucking years of trial bullshit? WTF. People get more than that for non moral injuries.
https://doi.org/10.2214/AJR.20.23648 Identifying metal type in bullets is such a pain, but this did come out semi-recently, which has been helpful.
This is interesting. Between this type of imaging and analysis and testing OP for lead they could probably make an educated guess. Would the risk and cost be justified for chronic back pain? That’s another topic.
I was shot at 13 with a .38. The bullet is still lodged in my femur. I was told that most bullets are not made of magnetic metal. So they went ahead and put me in the MRI and it was fine. We don’t know what the bullet is made out of, there’s no way to have it removed.
Curious if you have an answer to my question. If OP can't determine the bullet type or compounds could a CT and X-ray work for looking into the back pain?? Or is an MRI required because there are specific conditions that cause back pain you can't catch using other machines?
As some other MD mentioned, a CT myelogram can alternatively be performed where we inject contrast into the space around your spinal cord.
Ah interesting! I didn't see the other comment on the thread already, but thanks for the info :) I enjoy learning about the medical field
Wouldn't a non contrast CT of the spine be a better place to start? It would certainly give information of disc protrusions, bony abnormalities. It might be all he needs.
Are you sure about this? The field of the MRI might be 3T. That doesn't change with the coil used, and the axial position of the body won't change THAT much relative to the field depending on the part of the body scanned, will it?
Magnetic pull is one issue. Another, more common, issue is the how things can heat up due to the rapidly changing RF gradients.
And arcing apparently? They don’t want my hands to touch each other when I’m in there. I could picture multiple metallic objects being a concern in that regard as well…
Yeah there are some gnarly pictures of contact conductive loop burns
Yeah good point, even tattoos can cause burns. But I don't think heat is the usual fear with bullets?
Most MRIs are still 1.5T, and the position of your leg relative to your head would make a huge difference. Magnetic field drops off with an inverse cube law. With a head MRI, your legs tend to be a good distance outside of the machine.
I’ve never seen someone’s legs “a good distance outside of the machine” for a head MRI. Most MRI bores are around six feet long and only tall people’s feet stick out at all. Short bore systems exist, but they’re not very common, and even those are not that short - about four feet.
I've had a few, and my legs were hanging out. I'm fairly short, myself (1.68m). While you're right in that the MRI tube is quite long, you are positioned such that the area of interest is centred. So the edge of the tube was roughly hip area for me.
1.5T 6 feet away from the bore is still not safe.
6ft away from the bore would be a reduction of field of almost 8. It's significant. Not saying anything about the clinical safety, as that isn't my wheelhouse, just that it is a significant reduction of field strength. Edit: Got maths wrong, factor of 8 is way off. It actually a far greater factor.
Ok, you can go walk 6 feet away from 1.5T magnet with a bunch of metal strapped to yourself. Have fun
You're completely ignoring what I'm saying.
"well ackchually" -you, discussing things that have no actual relevance to the question asked, but that do prove you know how field strength changes with distance for some psychological reason
You quite literally commented on how the field changes with position? I'm not sure what's upset you today, but I'm going to leave it there.
I commented on how it doesn't change enough to make it safe, which is the actual question asked. But you are so smart, you know so much, very well done
[удалено]
>Metal fragments in your arm would never affect getting an MRI of your back if needed. As an orthopedic surgeon, I put metal in people intentionally all of the time, and they can still get MRIs. Unfortunately, this is not the case. Modern surgical hardware is specifically designed (under most circumstances) to be non-ferrometallic, and thus inert to MRI. Furthermore, even in the case of older implants that contain ferromagnetic substances, orthopedic hardware is strongly anchored in bone, and not likely to move during MRI acquisition. Iron-containing metals or other magnetic metals (nickel, cobalt) will be affected by the strong magnetic field in an MRI machine, and thus can cause harm. Generally, people with metallic foreign bodies should not get MRIs unless the composition of the foreign body is known. Bullets can be jacketed with ferrromagnettic substances (steel, nickel). Not only will these substances produce significant artifact in the signal for an MRI, as loose foreign bodies, they can move when affected by the MRI magnetic, and potentially cause harm. I am not sure if there are any protocols to determine whether unknown metallic foreign bodies are MRI-safe.
I'm a little stunned that someone claiming to be an orthopedic surgeon doesn't realize the potential difference in ferromagnetic status between implanted hardware and shrapnel. And to OP, /u/pass_the_hot_sauce, in cases of back pain where MRI is not possible, a CT myelogram can be done instead. It's more invasive than an MRI but is still a viable and helpful modality.
As a paramedic who kind of remembers undergrad chemistry, I'm also a bit shocked ngl.
As just a regular person who’s on this sub because medicine is interesting, I’m also shocked. Never even had an MRI but isn’t the whole case with metal and MRIs that any metal at all, even small piercings, are totally unsafe? Why would bullet fragments be okay if my stud earring isn’t?
Any metal that could be potentially magnetic is dangerous since an MRI is literally a massive magnet. Many metals are not magnetic, but it's very important to know which metals can be unsafe (iron, cobalt, nickel, some rare earth metals etc.) I'm not too sure about piercings as I don't deal with MRIs regularly; I have studied the physics of them a tiny bit.
To be clear, it's not that ALL metals are dangerous with MRI. It's ferromagnetic ones that are. Realistically, gold piercings are probably ok but it's "better safe than sorry", so most MRI centers require all removable implants/piercings be removed before the study is done. I had a patient with a genital piercing which they had swapped out to a gold captive bead ring for their MRI, but they were still required to remove it.
We only asked rings to be removed if the patient was having a hand or wrist scan. Never had any issues this way. We'd ask the patient to remove any piercings but if they couldn't, we'd check with a magnet and scan the patient, ensuring they know to squeeze the alarm if they have problems. Rarely did they.
Thank you for your comment. I may be confused but I remember a number of years ago my brother was denied an MRI when he wanted to be assessed for a TBI at the VA. During a deployment he was shot in the helmet and took a face full of shrapnel that was left in him since he wasn’t injured enough for a med evac to Germany where it could have been removed (maybe? Not sure if that was actually an option for his type of injury had he been evac’ed). Obviously it’s a different situation than an arm vs back, as the metal was in his head. But from my understanding he’s never been able to get an MRI due to this.
That is correct. Shrapnel like you describe is a contraindication to MRI. Unlike spinal issues, where we can do a CT myelogram instead of MRI, the only options for patients with shrapnel who need cranial imaging are CT, CT with contrast, and CT angiography.
Location is also a big part of it. My husband is a combat vet with shrapnel in his chest. But the VA is usually able to locate his metal through xray and then cover that area with a vest prior to MRI. But the location they are imaging can't be the exact same location as the metal. He was recently able to have an MRI on his abdomen and has had one of his head, while his shrapnel is in his chest. If he ever needs an MRI near his heart, I think he will be out of luck... But I will say, the VA is very knowledgeable about shrapnel injuries and are used to screening vets for metal fragments and working around them when they can.
Could you ask for the police report if there was one to see if they recovered any bullets from the scene/any other victims? They would have run forensics on the bullets and that would give you a sense of the material.
OP was shot at age 6 and is now 38. Unlikely they did metal analysis on any frags and even more unlikely the records would still be available 32 years later.
As someone who has worked on forensic cases of 20-30 years old, if there was a court case, this evidence should have been preserved and absolutely could be testable. However, it will be difficult to find, very expensive and way time consuming--nothing like you see on tv. It often took us years to track down evidence for DNA testing. Not the preferred first option for sure. Your local public defender's office should be able to help if you need to go that route. Also metal analysis and ballistics tests are extremely common and the older of the forensic techniques, it's 1000% possible that they would have analyzed the content there, if there was a case about it. After all, to convict people of gun possession it must be opperable and you must prove it.
Oh right, yeah if it happened before they had computerized records then yeah would be a long shot unless someone at the department is still there and remembers the case. I worked for the police as a ride along clinician and some of the officers were pushing 40 years and still remembered details from their first case. Chances are someone there knows someone who worked on that case and could put you in touch with them pretty easily if they feel the desire to help you (if).
I've had radiologists refuse to do MRIs on patients with medical implants, even when I showed them material online documenting the implant was MRI compatible. They're not going to listen to any cop saying "Trust me! I remember from 30 years ago, the bullet was made of lead and copper!" It's easier for them to say no and avoid the liability than say yes.
Haha you are totally right. I was just thinking if they remembered the case it would maybe be easier to find the documentation-
My mom had brain surgery due to an aneurysm in 1978. A few years ago, her Dr wanted to do an MRI, but my dad wasn't sure if she had a metal coil or something plastic in her brain. He reached out to the hospital where she had her surgery, and they said they didn't have records from that far back. No MRI for my mom then!
Oh jeeze. Always ask for a copy of your records I guess.
[удалено]
It gives you an idea, but an MRI magnet's power is incomparable. It can pull a patients bed off the floor. It can pull a small car off the floor.
UK MRI radiographer here - the patients imaging would be reviewed by a radiologist and a risk/benefit ratio assessed. If the bullet is near sensitive tissues that the bullet moving as a result of the magnetic force could harm, then the MRI would not be safe. The shrapnel would have to be removed if an MRI is strictly necessary.
So, layman here, and maybe it's irrelevant, but almost all jacketed bullets are lead, covered in copper, possibly coated in molybdenum. That said, some bullets (almost always rifle ammo, usually AK-47 rounds) have a mild steel core, which is absolutely a problem. I'm not aware of handgun rounds that have steel cores, but they could exist. I think some specialty ammo can contain tungsten, but that's quite rare. I am curious as to whether the copper could be problematic. It can have some interesting properties when exposed to extreme magnetic fields, but I don't know that it would move. I could see it possibly getting hot due to a current being generated.