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(Figure 1) shows a 1.0-cm-diameter loop with R = 0.50 inside a 2.0-cm-diameter s

ID: 3164197 • Letter: #

Question

(Figure 1) shows a 1.0-cm-diameter loop with R = 0.50 inside a 2.0-cm-diameter solenoid. The solenoid is 8.0 cm long, has 100 turns, and carries the current shown in the graph. A positive current is cw when seen from the left.

Determine the current in the loop at t = 0.010 s?

Express your answer with the appropriate units.

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 with a coil of very fine wire circling the edge. A current is induced in the coil each time the subject rotates his eye. Consider the experiment shown in the figure in which a 24-turn, 6.0-mm-diameter coil of wire circles the subject's cornea while a 1.0 T magnetic field is directed as shown. The subject begins by looking straight ahead.

What emf is induced in the coil if the subject shifts his gaze by 6 in 0.23 s ?

Express your answer to two significant figures and include the appropriate units.

2.0 cm 1.0 cm (A) r(s) .01 0.02

Explanation / Answer

emf E = d flux/dt = A dB/dt

but B comes from solenoid
B = u0 I N/L
there fore dB/dt = u0 N/L dI/dt
from figure dI/dt = 0.5/0.01
emf E = pi*(0.01/2)^2* 4*pi*10^(-7)*100/0.08*0.5/0.01=6.16*10^-6 V

I = emf/R = 6.16*10^-6/0.5=1.23*10^-5 A

hope it works :))