Thomson Tube

Item Code: SN1031

Principle and Working:

Thomson Tube is used to study the effect of electric and magnetic field on electron. A high voltage is applied between anode and cathode. Electrons are therefore emitted from cathode and accelerated towards anode. Cathode is maintained at ground potential. So electrons are emitted from cathode with a kinetic energy proportional to the anode voltage. These emitted electrons from cathode are then accelerated towards anode and pass horizontally through a slit behind the anode. vertical directions. ...

These energetic electrons then impinge upon fluorescent screen where they are observed. A plate capacitor is used to displace the electrons vertically upward or downward in fluorescent screen. Helmholtz's coils are used to produce a horizontal magnetic field which moves the electrons in the




  • Thompson Tube with built-in capacitor and fluorescent screen.
  • Helmholtz Coil (320 turns) for production of magnetic field.
  • DC High voltage power supply from 0-5 KV, fixed 6.3V AC.
  • DC multivoltage power supply 500V, 50V, 12V, 8V.
  • High current safety wires.

  • Investigate the deflection of an electron beam by a magnetic field.
  • Estimate the specific charge of an electron.
  • Investigate the deflection of an electron beam by an electric field.
  • Construct a velocity filter using orthogonal electric and magnetic field

  • Teltron tube : Max. filament voltage 6.3 V AC, Max. anode voltage 5 kV, Max. capacitor voltage 500 V, Anode current 0.1 mA at 4 kV (anode) .008m between tick marks on screen
  • Power Supply : Voltage 0-5KV DC, max. 2 mA, Heater voltage 6.3 V AC, max. 3 A, Overload protection fuse & current-limiting resistors, 4mm safety sockets, High-voltage display Analogue, Weight 3.5 kg approx.
  • Tube Holder : 4mm safety sockets, Dimensions 130 x 190 x 250mm³, Weight 570 g.
  • Safety Leads : Wire cross-section 2.5mm2, Continuous current 32 A, Plug and jack 4mm, Qty. 15, Length 75cm, Color – red, black and blue.
  • Helmholtz coil pair : Number of turns 320, Coil diameter 138mm, Load rating 1.0 A (Continuous operation), 1.5 A (Short-term operation), Effective Impedance 6.5Ω, Terminals 4mm safety sockets, Max. field strength 9 mT
  • 1 Power Cord
  • 1 Teltron Thompson Tube S
  • 1 Tube Holder S
  • 1 Pair of Helmholtz Coils
  • 1 Power Supply 5 kV
  • 1 Power Supply 0 – 500V,
  • 1 Set of 15 Safety Experiment Leads, 75 cm