A coil with turns given magnetic field, time find the emf induced in the coil

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Homework Help Overview

The discussion revolves around calculating the induced electromotive force (emf) in a coil subjected to a changing magnetic field. The problem involves a coil with a specified number of turns, area, and a magnetic field strength, as well as a time interval for the rotation of the coil.

Discussion Character

  • Exploratory, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants discuss the calculation of magnetic flux before and after the coil's rotation, with some verifying their results and others questioning the correctness of their calculations. There is a focus on the formula for emf and the need to ensure accurate values for area and time.

Discussion Status

The discussion is active, with participants sharing their calculations and seeking clarification on the results. Some guidance has been offered regarding the need to check the area conversion and the calculation process, but no consensus has been reached on the correct emf value.

Contextual Notes

Participants are working under the constraints of specific values provided for the magnetic field and the dimensions of the coil, as well as the requirement to convert units appropriately. There is an emphasis on ensuring accuracy in calculations without providing direct solutions.

sonrie
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A coil with 240 turns enclosing an area of 13.7 cm^2 is rotated in a time interval of 3.70×10^-2 s from a position where its plane is perpendicular to the Earth's magnetic field to one where its plane is parallel to the field. The Earth's magnetic field at the lab location is 5.9×10−5 T .

What is the total magnetic flux through the coil before it is rotated?
I found this answer its 1.9*10^-5 WB.

What is the total magnetic flux through the coil after it is rotated?
I found this answer its 0 WB.

What is the average emf induced in the coil?

I'm having trouble getting the right answer! I get 1.27*10^-7 but its wrong! Help Please!
 
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sonrie said:
What is the total magnetic flux through the coil before it is rotated?
I found this answer its 1.9*10^-5 WB.
Double check the exponents in this answer.

What is the total magnetic flux through the coil after it is rotated?
I found this answer its 0 WB.
Good.

What is the average emf induced in the coil?

I'm having trouble getting the right answer! I get 1.27*10^-7 but its wrong!
How did you get this?
 
the equation is emf = -N BA/T

-240 5.9*10^-5*.137/5.9*10^-5=3.28*10^-9 its still wrong
 
sonrie said:
the equation is emf = -N BA/T

-240 5.9*10^-5*.137/5.9*10^-5=3.28*10^-9 its still wrong
You have the correct formula, but you need to redo the calculation more carefully:
(1) You have the incorrect area. (Note that 1 cm^2 = 10^{-4} m^2.)
(2) Divide by the time interval.
 
Thank you!
 

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