1. Wrapping up chapter
12.1

2. REMINDER Monday-April 18th (2011) YES, A Monday
Examination #3 is scheduled for
Monday-April 18th (2011)
YES, A Monday

3. April 2011 1 2 3 4 Complete Induction 5 6 AC 7 8 Quiz? 9 10 11 OPTICS
Sunday
Monday
Tuesday
Wednesday
Thursday
Friday
Saturday 1 2 3
4 Complete Induction 5 6 AC 7 8
Quiz? 9 10 11
OPTICS 12
13 OPTICS 14
15 OPTICS
Quiz 16 17 18
EXAM #3
(No Optics) 19
20 OPTICS 21
22 OPTICS 23 24
25 (LAST LASS) 26 27 28 29
30 FINAL
HPA 119
9:00 AM

4. Self-inductance –
Any circuit which carries a varying current self-induced from it’s own magnetic field is said to have INDUCTANCE (L).

5. Faraday says this is the emf!
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
Inductance Defined
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Induction

6. So … E= The UNIT of “Inductance – L” of a coil is the henry. SYMBOL:
(-) sign is Lenz’s Law
The UNIT of “Inductance – L” of a coil is the henry.
SYMBOL:
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Induction

7. Remember that a Capacitor stored ENERGY? U=(1/2)CV2
U=Area=(1/2)LI2 i Li LI Li DU i Di I
Induction
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Induction

8. SO …
Energy Stored in a capacitor
The energy stored in a capacitor with capacitance C and a voltage V is
U=(1/2)CV2
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Induction

9. 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.
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Induction

10. Energy Storage in Inductor
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Induction

11. Up and Down and Up and Down and …..

12. NEXT AC
Circuits
But …

13. Finish Working it…..