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Electromagnetic Testing

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Impedance<br />

To explain the addition of reactance and resistance witha minimum of<br />

mathematical calculations, it is ·possible to use vector or phasor diagrams. A<br />

vector diagram constructed with imaginary units on the ordinate or Y axis and<br />

real units on the abscissa or X axis is shown in Figure 3.2. Z=√(X L2 +R 2 )<br />

Observation of Figure 3.2 reveals X L , R and<br />

Z appear to form the sides of a right triangle.<br />

The mathematical solution of right triangles<br />

states the square of the hypotenuse is equal<br />

to the sum of the squares of the other two<br />

sides, or c 2 = a 2 + b 2<br />

Figure 3.2 Vector Diagram<br />

Substituting Z, X L and R, the statement<br />

becomes: Z 2 = X L2 + R 2 , further simplified<br />

Z = √(X L2 +R 2 )<br />

Charlie Chong/ Fion Zhang

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