Step 1: Understanding the formula for resonant current.
At resonance, the impedance of the circuit is purely resistive, and the current is determined by Ohm’s law:
\[
I = \frac{V}{R}
\]
where \( V \) is the voltage and \( R \) is the resistance. At resonance, this equation gives the resonant current \( I_0 \).
Step 2: Formula.
Substituting \( V = 120 \, \text{V} \) into the formula:
\[
I_0 = \frac{120}{R}
\]
Thus, the resonant current is \( \frac{120}{R} \), where \( R \) is the resistance of the circuit.
Step 3: Conclusion.
The resonant current is \( \frac{V}{R} \), which is determined by the applied voltage and the resistance.