51. Two isotopes leave the slit at point S and into a magnetic field of magnitude 0.100 T pointing into the page, each has speed of 1.00 x 106 m/s. The first one contain one proton and has a mass of 1.67 x 10-27 kg and the other contains a proton and a neutron and has a mass of 3.34 x 10-27 kg. What is the distance that they could be separated when they strike a photographic plate? (e = 1.6 x 10-19C)
(A) 0.520 m
(B) 0.313 m
(C) 0.210 m
(D) 0.105 m
(E) 0.104 m5d073137ef6f7.jpg

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統計： A(2), B(1), C(39), D(1), E(9) #2016153

詳解 (共 2 筆)

#3493308
帶電質點進入與運動方向垂直的磁場會受洛仁...

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#5373673

r= mv/qB,

題目所求D = △2r =  2 (m1-m2) v / qB (v,B題目指均為v=106, B=0.1)
如此一來代入算一算即為答案

流氓排除法：(D)(E)選項太靠近，出題者為避免正確答案的計算誤差，通常這兩個都不會是答案

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