學士後西醫-物理題庫下載題庫

46. As shown in the figure, a small particle of charge q= -7.0 x10^-6 C and mass m=3.1 x10^-12 kg has velocity v=9.4 x10³ m/s as it enters a region of uniform magnetic field. The particle is observed to travel in the semicircular path shown, with radius R = 5.0 cm. Calculate the magnitude of the magnetic field in the region.
(A) 0.26T
(B) 0.20T
(C) 0.14T
(D) 0.08T
(E) 0.02T