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B In layman's terms , how strong is a 3 Tesla Magnet?

  1. May 10, 2018 #1
    I saw a post where someone was granted access to a 1.5 Tesla MRI. After some research I discovered a 3 Tesla MRI. How strong is this magnet?
  2. jcsd
  3. May 10, 2018 #2


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    3T is a very strong magnetic field, and dangerous if you have anything magnetic nearby. This many times higher than the surface magnetic field of a neodymium magnet.

    To answer your question, it is important to distinguish between a magnet and a magnetic field. A magnet is an object that has a magnetic field around it. A small magnet can have the same surface magnetic field as a large one, but a large one will have a much higher pulling force over a much larger distance. So, the pulling force of a magnetic field depends on the geometry of the magnetic field. That said, an MRI machine can produce frighteningly strong fields.
  4. May 10, 2018 #3

    Vanadium 50

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    Twice as strong as 1.5 T!

    Seriously, what kind of answer are you looking for?
  5. May 10, 2018 #4
    A magnet that produces a 1 T field will pull 58 PSI on a steel surface. That's pounds per square inch of pole area contacting the surface. It is very roughly the strength of a neodymium iron boron magnet in contact with a thick piece of steel. A neo magnet of size 1" X 2" X 2" is too strong to safely hold in your hand if there is any steel or other neo magnets nearby.

    The pull force is proportional to the square of the field strength, so a 3 T magnet will pull 9 X 58 = 522 PSI.

    I had to study up on this some years ago when I designed an electromagnet to pull 1600 lbs force through a 1/4" air gap. And was amazed when it actually worked according to the calculations.
  6. May 10, 2018 #5


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    For comparison: An automobile tire puts a few tens of psi on the ground to support the weight of the automobile - and you will be going to the emergency room with some broken bones if you get your foot caught between the tire and the ground. This magnet is doing ten times that.
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