induced current A circular loop in the plane of a paper lies in a 0.85 T magneti
ID: 3896794 • Letter: I
Question
induced current
A circular loop in the plane of a paper lies in a 0.85 T magnetic field pointing into the paper. The loop's diameter changes from 23.0 cm to 5.6 cm in 0.55 s. What is the direction of the induced current? What is the magnitude of the average induced emf? Express your answer to two significant figures and include the appropriate units. What is the average induced current if the coil resistance is 4.3 ohm ? Express your answer to two significant figures and include the appropriate units.Explanation / Answer
emf=B delta (A)/delta (t)
emf=B ( A final-A initial)/ delta t
where...delta t=0.55 sec, A final=pi(0.056/2)^2 and A initial=pi(0.23/2)^2 and B= 0.85 tesla
Clockwise
emf = 0.85 * 3.1415 * ((0.056/2)^2 - (0.23/2)^2) / 0.55 = -0.0604 V
I = V/R
I = 0.0604 / 4.3 = 0.01404 A
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