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© 2013 Pearson Education, Inc.
Exercise Bike and Eddy Currents
© 2013 Pearson Education, Inc.
© 2013 Pearson Education, Inc.
Detecting Flaws in Airplane Wings With Eddy Currents
© 2013 Pearson Education, Inc.
Immediately after the switch is closed, the lower loop exerts ____ on the upper loop.
A. a torque
B. an upward force
C. a downward force
D. no force or torque
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If the current in the straight wire is decreasing then
A. a force pushes the loop to the right
B. a force pushes the loop to the left
C. there is no net force on the loop
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Coil Puzzle
Disconnecting the battery causes the disk to rotate: which way and why?
Is conservation of angular momentum violated?
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The magnetic field strength is decreasing. Which is the induced electric field?
E. No electric field is induced here.
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Examples of Inductors
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Inductors used in Apple Power Supply
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What are Inductors Good For?
●Storing, releasing energy (like capacitor)●Timing circuits (with resistor)●Oscillator (with capacitor)●Resonant tuning (with capacitor and resistor)
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Other Circuit Elements
Diode
Transistors
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Which current is changing more rapidly?
A. Current I1.
B. Current I2.
C. They are changing at the same rate.
D. Not enough information to tell.
© 2013 Pearson Education, Inc.
© 2013 Pearson Education, Inc.
What is the battery current immediately after the switch has closed?
A. 0 A
B. 1 A
C. 2 A
D. Undefined
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What is the battery current immediately after the switch has been closed for a very long time?
A. 0 A
B. 1 A
C. 2 A
D. Undefined
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Back EMF (MIT Demo)
https://www.youtube.com/watch?v=aSmMFog10D0
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Make-Before-Break Switch for Inductors
More familiar switch is “break-before-make”
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If the top circuit has an oscillation frequency of 1000 Hz, the frequency of the bottom circuit is
A. 500 Hz.
B. 707 Hz.
C. 1000 Hz.
D. 1410 Hz.
E. 2000 Hz.
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Which loop has the larger magnetic flux through it?
A. Loop A.
B. Loop B.
C. The fluxes are the same.
D. Not enough information to tell.
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The induced emf around this loop is
A. 200 V.
B. 50 V.
C. 2 V.
D. 0.5 V.
E. 0.02 V.
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Flux Through Solenoid
a b c d
Order of loops from largest to smallest magnetic fluxes is (assume B=0 outside of solenoid to good accuracy) : a) a > b > c > d. b) a = b > c > d. c) d > a > b > c. d) c > b > a > d. e) Some other order.
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The metal loop is being pulled through a uniform magnetic field. Is the magnetic flux through the loop changing?
A. Yes.
B. No.
© 2013 Pearson Education, Inc.
The metal loop is rotating in a uniform magnetic field. Is the magnetic flux through the loop changing? A. Yes.
B. No.
