Planck's Constant By Led

Item Code: SK014

Principle and Working:

The photon energy calculated by Einstein equation E=hv is equal to energy gap Eg between the valence and conduction bands. The energy Eg is equal to the energy barrier eV0, that electron have to overcome in going from n-doped side of diode junction to p-doped side when no external voltage V is applied to the diode. ...
In the p-doped side, electron recombine with holes releasing the energy Eg in the form of photon is given by equation
Eg = eV0
In the present setup ,the Planck Constant is given by
h = eV0λ/c
Where, V0= V-[(∆In I)/ ∆T-1 X k/e Xƞ]




  • Variable Voltage source 0-2V , Resolution 1mV.
  • Measuring Current meter 0-20mA, Resolution 0.001mA.
  • Built-in Temperature sensor in Oven.
  • Variable temperature control unto 65° Celsius.

  • Determination of material Constant h.
  • Determination of Temperature Coefficient of Current.

    • Determination of Planck’s Constant by LED method.

  • Plank constant : V-I and T-I mode, In V-I mode Display 3½ digit, 7segment LED, Voltage Range 0.000- 2.000V, Current Range 0-2000mA In T-I mode, Display 3½ digit, 7segment LED, Current Range 0-20mA, Temp. Range ambient to 65.0°C,
  • Oven : Temp. sensor Pt100, Heating Element 20Ω Heater at pin 4 & 5, Temp. sensor at pin 1 & 2, Oven Connector 5 Pin DIN type, LED Connector 3 Pin, DIN type
  • Sample LED’s : Yellow, Dia. 5mm, Wave length 590nm Red, Dia. 5mm, Wave length 700nm Orange, Dia. 5mm, Wave length – nm
  • 1 Planck’s constant apparatus
  • 1 Oven
  • 1 LED red
  • 1 LED yellow
  • 1 LED Orange
  • 2 LED Green
  • 1 Power cord