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posted by  showoff134 on 6/28/2008 11:20:04 PM  |  status: Closed  

Magnetic field creating an emf multiple choice question HELP!!!

Course Textbook Chapter Problem
Calculus Based Physics Fundamentals of Physics Extended (8th) by Resnick, Halliday, Walker N/A N/A
Question Details:
A merry-go-round has an area of 300 m2 and spins at 2 rpm about a vertical axis at a place where the Earth's magnetic field is vertical and has a magnitude of 5x10-5 T.  The emf around the rim is:
A. 0
B. .5mV
C. 3.1mV
D. 15mV
E, 30mV

I think the answer is zero because the only way a magnetic field can create an emf is if the magnetic field is changing or the area is changing, but I'm not positive and any help would definitely be a lifesaver.
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posted by Kayen on 6/29/2008 1:33:22 AM  |  status: Live
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showoff134's comment:
"thank you"
Response Details:
Choice A; Zero is correct.
 Induced emf is e = dφ/dt = 0
as  φ = B.A = B.A cos θ = 0
where θ the angle betwen vertical fied and area vector(horizontal) is 90o.
 
Kayen (Enjoys helping you uderstand..)
Please do not forget to Rate my Response.
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posted by showoff134 on 6/29/2008 1:34:22 AM  |  status: Live
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Response Details:
and why?
Oracle
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posted by zsm28 on 6/29/2008 1:54:45 AM  |  status: Live
Asker's Rating: Helpful   
showoff134's comment:
"other guy got here first"
Response Details:
the answer is zero because no magnetic flux passes through the area and is always zero.
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