Fields and Waves Lesson 4.5 INDUCTANCE Darryl Michael/GE CRD

Inductances self inductance - e.g. inductors Two types of Inductances: mutual inductance - e.g. transformers Self Inductance: coil of wire with , creates wire loop intersects this creates

Self Inductance For 1 turn: For N turns: , and is independent of I Do Problem 1 For 1 turn: For N turns: , and is independent of I Since L depends on materials (through m) and geometry (like C)

Self Inductance In general: x N, because , because x N, because Note: To calculate L, don’t need Faraday’s Law just need: The flux linkage, , only if all loops intersect same flux not true for finite solenoid and will need: Computation of Can use either method Do problem 2

Mutual Inductance Coil 1 Coil 2 Current through Coil 1 induces e.m.f. in Coil 2 Mutual Inductance:

Mutual Inductance Mutual Inductance where, Also, And, Do Problem 3b