# Question about changing magnetic flux

by Dany7777777
Tags: magnetic flux
 P: 1 1. The problem statement, all variables and given/known data A 200-loop coil of cross sectional area 8.5 cm2 lies in the plane of the page. An external magnetic field of 0.060 T is directed out of the plane of the page. The external field decreases to 0.020 T in 12 milliseconds. What is the magnitude of the change in the external magnetic flux enclosed by the coil? 2. Relevant equations $\Phi$m = A * B 3. The attempt at a solution Ive tried solving for both values of magnetic flux at each time and finding their difference. However, I still seem to get it wrong. I dont know If I am missing something, any help or tips would be greatly appreciated.
 P: 103 i believe it would just be the initial flux - the final flux... the full equation you want is $\Phi$= N*B*A*cos($\phi$) (N = the number of turns of the coil) however the direction of the area and the magnetic field are the same so cos(phi) = 1 just convert 8.5 cm2 to m2 which is 8.5 * 10-4 so.... N(.06T)(A) - N(.02T)(A), just plug in your numbers...i believe this is right anyway, someone should check my work

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