19. An electric field points into the page and occupies a circular region of radius 1.5 m, as shown in the right figure. There are no electric charges in the region, but a magnetic field forms closed loops pointing counterclockwise around the electric field region. The magnetic field strength 1.0 m from the center of the region is 2.5 µТ. What's the rate of change of the electric field?

(A)
(B)
(C)
(D)
(E)
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統計: 尚無統計資料
統計: 尚無統計資料