Click here to purchase the entire book in PDF format. Impedance Let's put an inductor in series with a resistor as is shown in Figure 2.35. Figure 2.35: A resistor and an inductor in series. Just like the case of a capacitor and a resistor in series (see section 2.4), the resulting load on the signal generator is an impedance, the result of a combination of a resistance and an inductance. Similar to what we saw with capacitors, there will be a phase difference of 90$^\circ$ between the voltages across the inductor and the resistor. However, unlike the capacitor, the voltage across the inductor is 90$^\circ$ ahead of the voltage across the resistor. Since the resistance and the inductive reactance are 90$^\circ$ apart, we can calculate the total impedance - the load on the signal generator using the Pythagorean Theorem shown in Equation 2.89 and explained in Section 2.5. $$Z = \sqrt{R^{2} + X_{L}^{2}}$$ (3.89)