Fine Bean Tube Basic Experiment

The Fine Beam Tube with Helmholtz Coils is designed to study the motion of electrons in a uniform magnetic field and to determine the specific charge (e/m) of an electron. The apparatus demonstrates the deflection of an electron beam into circular and spiral paths under the influence of a magnetic field generated by Helmholtz coils. The illuminated electron beam allows clear observation, making it an effective teaching tool for advanced physics laboratories. Manufactured by Atico Export India.

Principle

The Fine Beam Tube is used to investigate the deflection of cathode rays in a uniform magnetic field produced by a pair of Helmholtz coils. It also enables the quantitative determination of the specific charge (e/m) of an electron. Inside the glass bulb, an electron gun consisting of an indirectly heated oxide cathode, a Wehnelt cylinder, and a perforated anode generates an electron beam. The helium residual gas inside the tube becomes ionized along the electron path, producing a narrow, well-defined luminous beam. Measurement markings on the tube allow accurate and parallax-free determination of the beam's circular path diameter.

Objectives

• Study the deflection of electrons in a closed circular path inside a magnetic field.
• Determine the specific charge (e/m) of an electron.
• Observe the formation of closed circular and spiral electron paths.
• Understand the effect of a uniform magnetic field on moving electrons.

System Composition

Fine Beam Tube :

• 1 Pc

Fine Beam Tube Base :

• 1 Pc

Helmholtz Pair of Coils :

• 1 Pc

DC Power Supply :

• 1 Pc

Fine Beam Tube :

• Produces a bright and well-defined electron beam for clear observation.

Electron Gun :

• Consists of an indirectly heated oxide cathode, Wehnelt cylinder, and perforated anode.

Helium Gas Filled Tube :

• Helium residual gas produces a luminous electron beam through ionization.

Measurement Scale :

• Integrated measurement markings enable accurate and parallax-free determination of the beam diameter.

Helmholtz Coils :

• Generate a uniform magnetic field for controlled electron beam deflection.

Compact Experimental Setup :

• Designed for convenient operation and accurate experimental measurements.