Extra exam question E5C10

WhyA series circuit consisting of a 400-ohm resistor and a 38-picofarad capacitor at 14 MHz plots at Point 4 on Figure E5-1. A 38-picofarad capacitor at 14 MHz has a capacitive reactance of 1 divided by (2 pi times 14 MHz times 38 pF), which works out to about 300 ohms, so the series combination of a 400-ohm resistor and this capacitor plots at R equals 400 ohms, X equals negative 300 ohms on Figure E5-1, the coordinates matching Point 4 on the chart, answer B. None of the other labeled points on the figure sit at that specific resistance and negative-reactance combination.