In an $R L C$ series circuit, these three elements are connected in series: a resistor of $60.0 \Omega,$ a $40.0 \mathrm{mH}$ inductor, and a $0.0500 \mathrm{F}$ capacitor. The series elements are connected across the terminals of an ac oscillator with an rms voltage of $10.0 \mathrm{V}$. Find the resonant frequency for the circuit.