Electromagnetic Testing Eddy Current in Brief
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How eddy currents are created and sensed:<br />
An alternat<strong>in</strong>g current creates a magnetic field (Oersted's Law).<br />
The magnetic field causes a result<strong>in</strong>g eddy current <strong>in</strong> a part, which creates an<br />
<strong>in</strong>duced magnetic field (Faraday's Law).<br />
The magnetic field from the coil is opposed to the <strong>in</strong>duced magnetic field from<br />
the eddy current.<br />
A defect (surface or near surface) modifies the eddy current and therefore the<br />
magnetic field as well.<br />
This change <strong>in</strong> the magnetic field is detected by a sensor and is <strong>in</strong>dicative of<br />
a flaw.<br />
Charlie Chong/ Fion Zhang
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