question_answer

A beam of well collimated cathode rays travelling with a speed of \[5\times {{10}^{6}}\,m{{s}^{-1}}\] enter a region of mutually perpendicular electric and magnetic fields and emerge undeviated from this region. If \[|B|\,=0.02\,T\], the magnitude of the electric field is                                                               [Haryana CEE 1996]

A)            \[{{10}^{5}}\,V{{m}^{-1}}\]    

B)            \[2.5\times {{10}^{8}}\,V{{m}^{-1}}\]

C)            \[1.25\times {{10}^{10}}\,V{{m}^{-1}}\]                       

D)            \[2\times {{10}^{3}}\,V{{m}^{-1}}\]