Velocity Selector Bout                         - - - - - - - - - - - - - - - -         v E +                             The magnetic field is uniform inside the dashed-line region. What speed will allow the proton to pass undeflected through region of uniform electric field?

Velocity Selector Bout                         - - - - - - - - - - - - - - - -         v v E + +                             When the electric and magnetic forces balance then the charge will pass straight through.

Also, we simplified the calculation by making perpendicular to Velocity Selector Bout         - - - - - - - - - - - - - - - -         v v E + +                             This only works if the electric and magnetic fields are perpendicular and oriented so that is antiparallel to Also, we simplified the calculation by making perpendicular to