Experiments to study vision often need to track the movements of a subject\'s ey

Question

Experiments to study vision often need to track the movements of a subject's eye. One way of doing so is to have the subject sit in a magnetic field while wearing special contact lenses that have a coil of very fine wire circling the edge. A current is induced in the coil each time the subject rotates his eye. Consider an experiment in which a 20-turn, 6.0 mm diameter coil of wire circles the subject's cornea while a 1.2 T magnetic field is directed as shown in the figure below. The subject begins by looking straight ahead. What emf is induced in the coil if the subject shifts his gaze by 6° in 0.20 s? •Could someone help me understand how to solve this? Do we convert degrees to radians?

My Notes 10 -/1 points KnightCP3 25.P.066 Experiments to study vision often need to track the movements of a subject's eye. One way of doing so is to have the subject sit in a magnetic field while wearing special contact lenses that have a coil of very fine wire circling the edge. A current is induced in the coil each time the subject rotates his eye. Consider an experiment in which a 20-turn, 6.0 mm diameter coil of wire circles the subject's cornea while a 1.2 T magnetic field is directed as shown in the figure below. The subject begins by looking straight ahead. What emf is induced in the coil if the subject shifts his gaze by 6° in 0.20 s? Cornea. 6.0-mm-diameter coil Eye Submit Answer Save Progress

Explanation / Answer

B=1.2, N=20,=6deg,d=0.006m, t=0.20s

We need to use Faraday’s law of induction,

emf=-Nd/dt

emf=(f-i)/dt

i=BA*cos0 = Br2cos0 = 1.2*3.14*(0.006/2)^2*cos0 = 3.3912*10^-5 Tm^2

i=BA*cos6 = Br2cos0 = 1.2*3.14*(0.006/2)^2*cos6 = 3.3726*10^-5 Tm^2

emf =-{20[(3.3726*10^-5)-( 3.3912*10^-5)]}/0.20 = 18.6*10^-6 V =18.6µV

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