General Physics 2 Induction 1

Exam 2• Thursday, March 24• 8 problems on the test• Problems will be taken from the 30 problems posted on

the class schedule website• https://sites.google.com/site/sienaphys140spring2011/home/schedule-2011

• Values will be changed.• Same grading strategy as before

• Take exam• Get grade for effort• Corrections with solutions• Regrade for correctness and need for correction

General Physics 2 Induction 2

More practice

• What is the direction of the induced current in the circular loop due to the current in the wire?

General Physics 2 Induction 5

Electric Generators

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Plug & Chug

• A simple generator is used to generate a peak output voltage of 24.0 V. The square armature consists of windings that are 6.0 cm on a side and rotates in a field of 0.420 T at a rates of 60.0 rev/s. How many loops of wire should be wound on the square armature?

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Transformers

• t in primary induces VS in secondary coil

• Works for AC only• DC voltages don’t have

changing B field

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Transformers

• Step-Up Transformer• Vs VP

• Step-Down Transformer• Vs VP

• Conservation of energy requires• PP = Ps

• IP VP = IS VS

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Plug & Chug

• A transformer has 320 turns in the primary coil and 120 in the secondary coil. What kind of transformer is this, and by what factor does it change the voltage? By what factor does it change the current?

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Self-Inductance

• changing current passes through a coil• produces changing B flux

• which induces an emf

• Induced emf opposes change in flux

inductance (H)

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Think-Pair-Share

• If the current in a 180-mH coil changes steadily from 25.0 A to 10.0 A in 350 ms, what is the magnitude of the induced emf?

The current in an LC circuit

The current in an LC circuit where the initial charge on the capacitor is Q0 is

The oscillation frequency is given by

Applications

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More Practice Problems

• Magnetism: Worksheets 5• Exploration in Physics• • In application folder• • Select E&M tab at the top• • Answer the questions under the Hints tab for• each of the following• • Lenz’s Law• • Cathode Ray Tube• • Trajectory in E and B fields