試題詳解

16.In a mass spectrometer, the initally stationary ion is accelerated by the electric field due to a potential V. The ion enters a separator chamber in which a uniform magnetic field B is perpendicular to the path of the ion. The magnetic field causes the ion to move in a semicircle, striking a photographic plate at distance x from the entry slit. Suppose that B 80mT and V 1000 Volts, and ion of charge q +1.60 ́ C strikes the plate at x 1.63m, what is the mass of the ion?
(A)185.7u
(B)204.9u
(C)224.6u
(D)241.5u
(E)267.8u