Planck’s Constant Experiments

Item Code: SN1068

Principle and Working:

The emission of electrons by a metal material when the latter is exposed to electromagnetic radiation of a sufficiently high frequency, is a means of approaching and better understanding the particulate aspect of light. The experiment proposed, using our photoelectric cell, a HP mercury spectral lamp and a micro-ammeter, aims at showing the photoelectric effect, verifying Einstein’s equation and experimentally measuring Planck’s constant. ...
To do this, the photoelectric cell, with a spectral range from approx. 340 to 700 nm, is installed in a metal box ensuring its light insulation and safety. A drum secured on the front of this box allows a variety of filters and diaphragms to be placed in front of the cell to perform a set of measurements. Last but not least, one device only is used to supply both the cell anode and cathode with two voltage ranges (-2/2 V and -2/30 V) and as micro- ammeters to measure photo-current (with a number of measurement ranges:
10-8 to 10-13 A).




  • High quality imported grating (100,300,600 line/mm).
  • Electrical safety tested high voltage power supply with over load current protection.
  • Tube filed with research-grade gasses & vapors.

  • To measure the current voltage characteristic of the photoelectric cell.
  • To determine the value of Planck’s constant "h".

  • Current measures : Range 10-8 -10-13 A, measurement ranges, Digital display on 4 digits, Zero drift
  • Cell supply : 2 voltage ranges, -2V/+2V ; -2V/+30V, Digital display on 4 digits, Resolution 0.01 V Stability <0.1 %
  • Photocell : Spectral response 340 to 700 nm, Nickel anode, Sensibility ≥ 1 μA/lm, Dark current I ≤ 2.10-12 A(-2V ≤ UAK ≤ 0V)
  • Filters : 5 filters on a cylinder 365.0 nm, 404.7 nm; 435.8 nm; 546.0 nm; 577.0 nm. Diaphragm 2 / 4 / 8 mm.
  • 1 planck constant setup power supply
  • 1 Photocell in Holder with stand
  • 1 Five color filter in one assembly
  • 1 Light Source with Stand