Planck’s constant compact apparatus

With this device, Plank?s constant can be easily determined to an error level around or better than 5 %.
Electron affinity can be calculated as well.
The phenomenon is termed the outer photoeffect.
Electromagnetic radiation results in the release of electrons from a metal surface.

The device has a built-in photodiode, LEDs of various wavelengths are used as monochromatic light sources.
The emitted light passes through the opening of the ring-shaped anode and contacts the surface of the cathode.
In the photoeffect, a photon transfers its entire energy (E = h * f) to an electron upon impact.
Part of the energy is required to force the electron out of the metal surface (electron affinity).
The remaining energy is then at the electron?s disposal as kinetic energy.

Ekin = h x f – ?

The critical voltage for the five available wavelengths is measured within this experiment.
All further calculations are based on this.

All required peripheral devices (voltmeter, nano-amperemeter) are integrated into the device.
The five light sources (LEDs with various precisely defined wavelengths) are supplied with power from the device.
Power supply through included fixed-voltage transformer.
Supplied with experiment manual as well as evaluation spreadsheet (Excel).

TECHNICAL SPECIFICATIONS
Photocell Material Caesium (Cs)
Voltmeter Display 3 ? digit, LCD
Voltmeter Precision 0,5 % (typical)
Amperemeter Display 3 ? digit, LCD
Amperemeter Precision 1 % (typical)
Dimensions W x H x D = 280 x 120 x 160 mm
Weight approx. 1000 g