question_answer

An electron moving with a speed u along the positive\[x\] -axis at \[y=0\]enters a region of uniform magnetic field \[\overrightarrow{B}\text{ }=-{{B}_{0}}\hat{k}\] which exists to the right of \[y\]  -axis. The electron exits from the region after some time with the speed v at coordinate y, then:

A)  v>u,y<0                     

B)  v=u,y>0

C)  v>u,y>0                     

D)  v=u,y<0