A circular coil of diameter 24 mm has 40 turns. The coil is placed in a uniform magnetic field of flux density 85 mT with its plane perpendicular to the field lines.
a) i Calculate the area of the coil
ii The flux linkage through the coil.
b) The coil was reversed in a time of 95 ms.
i the change of flux linkage through the coil.
ii the magnitude of the induced emf
Flux linkage = NBA
EMF = rate of change of flux linkage
The Attempt at a Solution
Part a I am ok with ai) area = 4.5x10^-4 and flux linkage is BNA = 1.53 mWb
In part b I struggled to see why the answer was 3.06 mWb and not a change of 1.53 to zero as it rotated.
my logic being that it changes from 1.53 to zero as it rotated for the first 90 degrees then back to 1.53.
I remember reading area is a vector so if this is true does it mean the flux linkage is changing from 1.53 mWb to -1.53 mWb, This would give me the correct answer in the back of the text book.
Is there anyway of seeing this without knowing that area is a vector as this is not in the text book as a principle taught on my course.
Thanks you for any help