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Electromagnetic Testing

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Figure 4.4: Fill factor ratios<br />

Whena nonfermmagnetic test object is inserted into the test coil, the coil's<br />

voltage will decrease.<br />

∆E = E o (1- η + η∙μ eff )<br />

∆E = 10 (1-0.81 + 0.81 x 0.3)<br />

∆E = 4.33 Volts<br />

This allows 10- 4.3 or 5.7 V available to respond to test object changes<br />

caused by discontinuities or decreases in effective conductivity of the test<br />

object. It is suggested that the reader calculate the resultant loaded voltage<br />

developed by a 12.7 mm (0.5 in.) bar of the same material and observe the<br />

relative sensitivity difference.<br />

Charlie Chong/ Fion Zhang

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