Resonance in an inductor affects voltage by determining the relationship between inductance and capacitance. The resonant frequency can be calculated using the formula w = 1/(LC)^(1/2), which leads to finding capacitance through manipulation of the equation. Understanding impedance and reactance is crucial, as they relate to how resistance varies with frequency. The discussion emphasizes the importance of grasping these concepts to solve related problems effectively. Mastering these principles will aid in tackling coursework questions on resonance and its implications.