Ohm's Law describes the relationship between voltage, current, and resistance in an electrical circuit. However, when it comes to inductance, Ohm's Law alone is not sufficient. Instead, we need to consider the concept of "reactance" and how it relates to voltage and inductance.
In an electrical circuit, inductance (L) is a property of an inductor, which is a passive component that resists changes in current flowing through it. Inductance is measured in henrys (H).
Reactance (X) is a concept that represents the opposition to the change of current flow in an inductor or a capacitor due to the change in voltage across it. For inductors, the reactance is called "inductive reactance" and is denoted by X_L. It is calculated using the following formula:
X_L = 2πfL
Where:
X_L = Inductive reactance in ohms (Ω)
π (pi) ≈ 3.14159
f = Frequency of the alternating current in hertz (Hz)
L = Inductance in henrys (H)
Now, the relationship between voltage, current, and inductance can be understood through the concept of impedance (Z), which is the total opposition a circuit offers to the flow of alternating current. Impedance is a combination of resistance (R) and reactance (X), and for an inductor, it is calculated as follows:
Z = √(R^2 + X_L^2)
Where:
Z = Impedance in ohms (Ω)
R = Resistance in ohms (Ω)
X_L = Inductive reactance in ohms (Ω)
In an ideal inductor (one with no resistance), the impedance is solely determined by the inductive reactance. As the frequency increases, the inductive reactance also increases. Consequently, the impedance offered by the inductor to an alternating current increases with frequency.
To summarize, Ohm's Law alone is not applicable to inductance. Instead, the relationship between voltage and inductance is expressed through the concept of inductive reactance, which is part of the impedance formula for an inductor in an alternating current circuit.