Inductance and Inductive Reactance Inductance - the characteristic of an electrical ckt that oppose any change in current Symbol is “L” measured in a Henry (H) Inductors – Coils, inductors, reactors or chokes

Faraday’s Law n States that the induced voltage depends on: u the number of turns in the coil, u The strength of the magnetic field u How fast the conductor cuts across the magnetic field

Lenz’s Law

Inductance n All ckts have conductors n Has its greatest impact when there is a change in current n Does not oppose current only the change in current n AC ckt current always changes do to the sine wave

Coil Inductance n Four factors u Number of turns in the coil u Diameter of the coil and length u Type of material u Number of layers of the windings

Power Loss in an Inductor n Copper losses uI2RuI2R n Iron – core inductors u Hysteresis loss u Eddy-current loss

Transformer Action n Mutual Inductance

Inductive Reactance n the reactance of an inductor is called inductive reactance. In other words, an inductors resistance in an AC circuit is called Inductive Reactance

Inductive Reactance  Reactance (x) is expressed in Ohms and Ohms law applies to inductive reactive circuits  Inductive Reactance represented by X L n Depends on: F Frequency usually 60 hz F Inductance of the coil (H) - henry

Inductive Reactance n As a Formula u X L = 2пfL F X L = inductive reactance Ω F П = 3.14 F f = Frequency in Hz F L = inductance in henrys

Voltage, Current and Inductance n Ohms Law

Sine Wave Pure Resistance

Sine Wave With Reactance

Phase Diagram

Power in an Inductive Circuit n Purely resistive n Inductive Reactance n Vars (Q) – volt amps of reactance n VA (S)- Volt amps n Power (P) – Power of load