MemoNick
1. A flat rectangular coil measuring 2cm x 3cm and having 60 tuns of wire is turned through 90 degrees in 0.2s. The flux density of the magnetic field is 0.30T. Please note that a diagram is also provided - basically the coil is first perpendicular to the field, then it's rotated so as to become parallel. (Note that there are two parts for this question - the part I'm having problem with requires to find the change of flux linkage)

I don't know which formula/e I should have used, although given the dimensions, I guessed I would have to use $\vartheta$ = BA

3. Since at first, the flux linkage is maximum, and when rotated the linkage is minimum (0), I was tempted to use $\vartheta$ = BA [initial] - BA [final, where B = 0]
Therefore: $\vartheta$ = 0.3 * 0.02 * 0.03 = 1.8 x 10-4Wb
Now, my question is - is my reasoning correct? Thanks in advance!

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Homework Helper
Gold Member
Welcome to PF!

Basically, you have the right reasoning. But the definition of flux linkage includes the number of turns of wire.

You might also need to consider the sign of the answer to indicate whether there was an increase or decrease in flux linkage.