Controls

Electric Field linearly accelerates $e^{-}$ from voltage in Electron Gun: Va
Magnetic Field circularly accelerates $e^{-}$ from current in Helmholtz coils through coils: Iα

Schematic Diagram

Schematic layout of the experiment about electron deflection in a magnetic field
Elctron gun in a Cathode ray tube
Picture of the real experiment for deflection of electrons in a magnetic field