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magnitude of induced emf problem . watch

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    Hi guys.
    i've managed to do all parts of the blow question but for the last part i keep getting wrong answer . any help?
    a circular coil of diameter 24mm has 40 turns. the coil is placed in a uniform magnetic field of flux density 85mT with it's plane perpendicular to the field lines. if the coil was reversed in a time of 95ms calculate:
    the magnitude of the induced emf. i've used the formula (change of flux/time T)xN but i keep getting wrong answer. here's other informations i've managed to calculate in other parts of the question:
    A=4.52X10^-4
    flux linkage=1.54x10^-4
    the change of flux linkage through the coil =3.08Wb.
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    (Original post by Alen.m)
    Hi guys.
    i've managed to do all parts of the blow question but for the last part i keep getting wrong answer . any help?
    a circular coil of diameter 24mm has 40 turns. the coil is placed in a uniform magnetic field of flux density 85mT with it's plane perpendicular to the field lines. if the coil was reversed in a time of 95ms calculate:
    the magnitude of the induced emf. i've used the formula (change of flux/time T)xN but i keep getting wrong answer. here's other informations i've managed to calculate in other parts of the question:
    A=4.52X10^-4
    flux linkage=1.54x10^-4
    the change of flux linkage through the coil =3.08Wb.
    The formula you need is:

    E = BAN\omega sin\omega t

    where:

    \omega = 2\pi f

    A = c.s.a.\  of\ the\ coil.
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    where A is concerned, can i just use the equation for calculating area of a circle?(pi r^2) .
    i don't really understand what each alphabet stands for for the equation you mentioned to calculate A
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    (Original post by Alen.m)
    where A is concerned, can i just use the equation for calculating area of a circle?(pi r^2) .
    i don't really understand what each alphabet stands for for the equation you mentioned to calculate A
    Yes, it's simply the area enclosed by the coil so A = \pi r{^2}

    B = flux density.

    N = number of turns in the coil.

    \omega calculated from 2 x 95ms period (1 complete rotation).
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    But angular velocity is equal to 2piF isn't?i did the area exactly like you mentioned but still the answer i got is different that what the text book says which is 33mv
 
 
 
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