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What is Eddy Current Testing ?
Apply a changing magnetic field to a piece of metal
- This causes electricity to invisibly flow in a loop inside
- This so-called eddy current has to stay inside the metal
- It cannot get across cracks or through corrosion, etc
So we have a current loop, how do we know where it is?
- Any electrical current generates a magnetic field
- The shape of the field depends on the path of the current
- Simply measure magnetic field of the eddy current
where it conveniently extends outside the metal