Maxwell’s Equations Fields, Patterns, Maxwell’s Equations and Begin Induction/Faraday’s Law 2049 SCALE-UP
MondayWednesdayFridaySaturday 14 Chapter 22 Gauss (Read rest of chapter) 16 (Read rest of chapter) 2 WebAssigns Chapter 22 Gauss 18QUIZ Chapter 22 Lentz & More 21 Chapter 23 Faraday 23QUIZ Chapter 23 Faraday HOLIDAY 28 Chapter 23 Faraday 30 Chapter 24 EM 2 Chapter 24 EM Optional Exam (22-24) 3 FINAL EXAM
THE EVAN SHOW
“Curly Field” No diverging source Diverging Field Point Sources Electrostatic Fields Magnetic Fields
Let’s apply this to the gap of a capacitor.
i i CHARGING OR DISCHARGING …. HOW CAN CURRENT FLOW THROUGH THE GAP In a FIELD description??
I=0
CoilCoil GalvanometerGalvanometer
Integral over a SURFACE
A
Observation Meter Deflects There must be an emf around the loops! Variables Direction Polarity Pitch Velocity
Aluminum Pipe
BB N S Induced Current N REPEL!! must There must be an Electric Field in the metal that is pushing the current!!
You said that there is a conducting loop. You said that there is therefore a current induced around the loop if the flux through the loop changes. But the beginning and end point of the loop are the same so how can there be a voltage difference around the loop? Or a current??? ‘tis a puzzlement!
DID I LIE??
Electric fields that are created by static charges must start on a (+) charge and end on a (–) charge as I said previously. Electric Fields created by changing magnetic fields (NON-Coulombic) can actually be shaped in loops.
Because you said that an emf is a voltage so if I put a voltmeter from one point on the loop around to the same point, I will get ZERO volts, won’t I? How can there be a current??
Is the WORK that an external agent has to do to move a unit charge from one point to another. But we also have (neglecting the sign): ss
E Conductor x x x x x x x
E Conductor x x x x x x x A AThe emf BZero CCan’t tell
Michael Faraday ( ) MINUS????
Q: Which way does E point? A: The way that you don’t want it to point! (Lenz’s Law). Lenz’s Law Explains the (-) sign!
In this case, 2 coils, each have the SAME emf so we add.. Ohm’s Law still works, so
Faraday’s Experiments ????
Insert Magnet into Coil
Remove Coil from Field Region
That’s Strange ….. These two coils are perpendicular to each other
All Involve Changing The Magnetic Flux through the Loops
Remember the Definition of TOTAL ELECTRIC FLUX through a CLOSED surface:
Magnetic Flux Applies to an OPEN SURFACE only. “Quantity” of magnetism that goes through a surface. surface
In the figure below a 120-turn coil of radius 1.8 cm and resistance 6.8 is coaxial with a solenoid with 209 turns/cm and diameter 3.2 cm. The solenoid current drops from 1.5 A to zero in time interval Δ t = 25 ms. What current is induced in the coil during Δ t? A
DONE