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Learn about self-inductance in circuits and how it relates to the change in magnetic flux and current. Discover the energy storage capabilities of capacitors and inductors. Explore the concept of inductance and its applications in AC circuits.
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Wrapping up chapter 12.1
REMINDER Examination #3 is scheduled for Monday-April 18th (2011) YES, A Monday
Self-inductance – • Any circuit which carries a varying current self-induced from it’s own magnetic field is said to have INDUCTANCE (L).
Inductance Defined If the FLUX changes a bit during a short time Dt, then the current will change by a small amount Di. Faraday says this is the emf! This is actually a calculus equation Induction
So … E= (-) sign is Lenz’s Law The UNIT of “Inductance – L” of a coil is the henry. SYMBOL: Induction
Remember that a Capacitor stored ENERGY? U=(1/2)CV2 U=Area=(1/2)LI2 i Li LI Li DU i Di I Induction Induction
SO … Energy Stored in a capacitor The energy stored in a capacitor with capacitance C and a voltage V is U=(1/2)CV2 Induction
The Energy stored is in the Magnetic Field Consider a solenoid with N turns that is very long. We assume that the field is uniform throughout its length, ignoring any “end effects”. For a long enough solenoid, we can get away with it for the following argument. Maybe. Induction
Energy Storage in Inductor Induction
NEXT AC Circuits But …