You want to build an AM radio that uses a series \(R L C\) circuit for tuning. The circuit consists of a \(30.0-\Omega\) resistor, a 15. 0- \(\mu \mathrm{H}\) inductor, and an adjustable capacitor. At what capacitance should the capacitor be set in order to receive the signal from a station that broadcasts at \(870 \mathrm{kHz}\) ? How would you make the tuning more selective?