Objects
Deflection of electrons in a closed circular path inside a magnetic field
Determination of specific change of an electron e/m
Principles
The fine beam tube is used for investigating the deflection of cathode rays in a uniform
magnetic field produced by a pair of Helmholtz coils (P338001). In addition, it can also be used for quantitative
determination of the specific charge of an electron e/m.
Located inside a glass bulb with a helium residual gas atmosphere is an electron gun, which
consists of an indirectly heated oxide cathode, a Wehnelt cylinder and a perforated anode. The gas atoms are ionized along
the path of the electrons and a narrow, well-defined, luminescent beam is produced. Incorporated measurement marks
facilitate a parallax-free determination of the diameter of the circular path of the beam deflected in the magnetic field.
