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The cross-section area of an adjustable single loop is reduced from 1.2 m^2 to 0.4 m^2...

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lkehoe | (Level 1) Valedictorian

Posted April 15, 2013 at 6:38 PM via web

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The cross-section area of an adjustable single loop is reduced from 1.2 m^2 to 0.4 m^2 in 0.25 seconds.  What is the average emf that is induced in this coil if it is in a region where B = 1.5 T downward, and the coil's plane is perpendicular to B?

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pramodpandey | College Teacher | (Level 3) Valedictorian

Posted April 16, 2013 at 5:40 AM (Answer #1)

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magnetic flux through coil area =1.2 sq m

`phi=BA`  Wb

`phi=1.5xx1.2`

`=1.8 `  Wb

`phi_1=BA_1`

`=1.5xx.4`

`=0.6`  Wb

change in magnetic flux=`Deltaphi`

so  we have

`Deltaphi=0.6-1.8`

`=-1.2`

`Delta t=0.25 `

emf=`(Deltaphi)/(Deltat)`

`=-1.2/.25`

`=4.8` V

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