Physics 122 - Lecture
Date: 4/27/16
Questions?
Announcements/Reminders
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Written HW #13 – Due Friday, April 29, in class.
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MP HW #13 – Due Friday, April 29, by 11:59 pm.
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Check website for reading assignment!
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Extra credit mini-test this Friday.
No make-up on this one!
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Exam #3 – May 4 or May 6 – see the study guide on the web.
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Final Exam – Tuesday, May 10, 1:30 pm, Workman 101.
Last class …
* * Electromagnetic Induction
* Motional EMF.
* Eddy currents.
Eddy Currents
“Swirling Current”
Clicker Question
A wire loop is in a uniform magnetic field. Current flows in the wire
loop, as shown. What does the loop do?
A) moves to the right
B) moves up
C) remains motionless
D) rotates
E) moves out of page
Clicker Question
A wire loop is in a uniform magnetic field. Current flows in the wire
loop, as shown. What does the loop do?
A) moves to the right
B) moves up
C) remains motionless
D) rotates
E) moves out of page
AC Generator …
- converts mechanical energy in electrical
https://www.youtube.com/watch?v=gQyamjPrw-U
Transformers
- ac current
Example 2:
The output voltage of a 75 W transformer is 12 V , and the input current is 22 A.
a) Is this a step-up or a step-down transformer?
b) By what factor is the voltage multiplied?
ConcepTest 29.12c Transformers III
A 6 V battery is connected
to one side of a transformer.
Compared to the voltage drop
across coil A, the voltage
2) 6 V
3) less than 6 V
4) zero
across coil B is:
A
6V
1) greater than 6 V
B
ConcepTest 29.12c Transformers III
A 6 V battery is connected
to one side of a transformer.
Compared to the voltage drop
across coil A, the voltage
2) 6 V
3) less than 6 V
4) zero
across coil B is:
A
6V
1) greater than 6 V
B