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Phy 242

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Test 3 Question

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A wire loop of radius a lies within the magnetic field of a planet, where is experiences a uniform magnetic field of strength T. The loop is oriented perpendicular to the field. The planet is daily eclipsed by a large moon, causing the loop to contract as it cools. If the radius of the loop as it contracts is a (b + (1-b) e^(-k t)), where b is a constant near 1, then what voltage is induced around the loop? Express the voltage as a function of clock time.

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I'm practicing for test three and came across this problem. This is how I think I'm supposed to solve it, but I'm not too sure.

induced voltage (emf)= -dmagflux/dt

induced voltage (emf)= -B*A

= -T*pi*(a(b+(1-b)e^(-kt)))^2

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Is this correct?

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Your expression for magnetic flux would be

T * pi * (a(b+(1-b)e^(-kt)))^2

That's the flux, not the induced voltage.

Take the derivative of this function in order to get the induced voltage.

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