In the following figure a beam of electrons is fired into the region of crossed electric and magnetic fields. E-intensity of electric field : B-magnetic induction field strength. If the velocity of the electron beam , $v>\frac{E}{B}$, then

 

force due to electric field eE is upward and due to magnetic field evB is downward

if eE= evB then it will go undeviated  then $v=\frac{E}{B}$

v is more than $\frac{E}{B}$ then force due to magnetic field will be stronger so it will get deflected downward