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Spoony
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Homework Statement
A small circular loop, radius a in the xy plane, carries current I which creates a magnetic moment pointing in the z direction. A magnetic induction field B= (s/y^3)z is applied to the loop where s is a constant, y is the distance in the plane of the loop from an arbitrary origin to the centre of the loop and z is a unit vector in the z direction. Assuming that a<<y, show magnetic energy is.
[tex] U = -\frac{s}{y^{3}} ( \pi a^{2} I [/tex]
hence determine the force on the loop in magnitude and direction.
2. Homework Equations &
3. The Attempt at a Solution
from what i know,
magnetic dipole m = I A
[tex] m = I \pi a^{2} [/tex]
induced magnetic field is in the positive z direction, i don't understand how the distance y comes into this though, magnetic fields fall off quickly so i can't see why itd be used..