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

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Discussion Overview

The discussion revolves around the strength of a 3 Tesla magnet, particularly in the context of MRI machines. Participants explore the implications of this strength in terms of safety and comparison to other magnets, such as neodymium magnets.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants note that a 3 Tesla magnetic field is significantly stronger than a 1.5 Tesla field and can be dangerous if magnetic objects are nearby.
  • One participant emphasizes the distinction between a magnet and a magnetic field, explaining that the pulling force depends on the geometry of the magnetic field.
  • Another participant humorously points out that a 3 Tesla magnet is twice as strong as a 1.5 Tesla magnet.
  • A participant provides a calculation indicating that a 1 Tesla magnet exerts a pull force of 58 PSI on a steel surface, suggesting that a 3 Tesla magnet would exert approximately 522 PSI based on the square of the field strength.
  • Further comparison is made to the pressure exerted by an automobile tire, highlighting the potential danger of a 3 Tesla magnet's pulling force.

Areas of Agreement / Disagreement

Participants generally agree that a 3 Tesla magnet is very strong and poses safety risks, but there are varying interpretations of its strength and implications, leading to multiple viewpoints without a clear consensus.

Contextual Notes

Some calculations and comparisons rely on specific assumptions about the geometry and conditions of magnetic fields, which may not be universally applicable.

Tech2025
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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?
 
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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.
 
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Tech2025 said:
How strong is this magnet?

Twice as strong as 1.5 T!

Seriously, what kind of answer are you looking for?
 
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.
 
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jrmichler said:
so a 3 T magnet will pull 9 X 58 = 522 PSI.
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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