作者nsh (>_<" )
看板Physics
标题[请益] 关於这题物理
时间Thu May 31 00:21:41 2007
A velocity selector uses a fixed electric field of magnitude E and the magnetic field is
varied to select particles of various energies. If a magnetic field of magnitude B is used to
select a particle of a certain energy and mass, what magnitude of magnetic field is needed
to select a particle of equal mass but twice the energy?
A. 0.50 B B. 1.4 B C. 2.0 B D. 0.71 B E. 1.7 B
请问有人会解嘛??
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