[填空题]
Near the equator, the Earth’s magnetic field pointfranqoa5 8rt5t7-y) rse )u) e*az 9dodv+csq(r23w gd almost horizontally to the north a)vq(e9o)sw a2 dgdec+ zrud*3nd has magnitude $B=0.50\times10^{-4}\mathrm{~T.}$ What should be the magnitude and direction for the velocity of an electron if its weight is to be exactly balanced by the magnetic force? $ \times10^{-6 }\;m/s$
