Higher Physics Lab Atomic & Nuclear Physics



Exp-1 To observe the neon spectral bands formation in Franck-Hertz tube.
Exp-2 To record the Franck-Hertz characteristic curve for neon.
Exp-3 To study the effect of filament voltage and anode plate voltage on the characteristic curve..

  • Manual & automatic experiment mode.
  • Neon bands formation in frank-hertz tube can be visually observed.
  • Easy experiment setup.
  • Auto identification of sensors and graphical analysis in automatic mode with data logger.
  • Excitation energy.
  • Electron collision.
  • Kinetic energy.
  • Energy level.
  • Ionization energy.

Frank Hertz Apparatus (SK090- consisting of CD133 & CD152) can be operated in stand alone mode.

Principle and Working:
The Franck-hertz tube consists of an electron-emitting cathode, two mesh grids for accelerating electrons and an anode plate for collecting electrons. It is filled with a low pressure gas. The mesh grids provide the accelerating potential to electrons and the anode is held at slightly negative potential to provide braking. At low accelerating potential, the electrons gain kinetic energy and reach the anode plate with purely elastic collisions with the gas atoms. As accelerating potential is increased the gas atoms absorb energy as they are excited due to in-elastic collision by the energized electrons. Thus fewer electrons reach the anode plate and there is a dip in the plate current. These dips in current is observed at approximately fixed intervals of accelerating potential which demonstrate the presence of discreet or quantum energy levels in the Bohr’s model of atom.
In the present Franck-Hertz experiment with neon gas, the absorbed energy by neon atoms is released through photons having red-orange wavelength, which can be visually observed in band formations. The experiment can be performed in manual mode where the accelerating voltage and the plate braking voltage can be manually controlled in SK090. Also with sensors and data logger in Sk087 the accelerating voltage can be automatically varied and plate current measured & displayed graphically on PC.


Cat. No. Item Name Qty.
CD133 Franck-Hertz unit 1
CD433 Data logger 1
C7994 Power supply for data logger 1
CD152 Neon tube with mount 1
CD435 Current sensor (± 100mA) 1
CD434 Voltage sensor (± 10V) 1
SN204 Flexible plug lead red 2
SN201 Flexible plug lead black 3
SN207 Flexible plug lead yellow 1
  USB cable 1
  Software CD disc 1

* Additionally Required:
Computer not supplied with this setup.

Atomic & Nuclear Physics Experiments