Which point on Figure E5-1 best represents the impedance of a series circuit consisting of a 300-ohm resistor and a 19-picofarad capacitor at 21.200 MHz?

الشرح

At 21.2 MHz the 19 pF capacitor presents about 395 Ω of reactance, which is negative, so the impedance is close to 300 − j395 ohms. On Figure E5-1 that is 300 to the right and 400 below the horizontal axis, which is Point 1; Point 3 is the inductive mirror image and Point 7 has a negative resistance.