For determining Planck's constant h by measuring the diffusion potential of differently colored LEDs as a function of the wavelength or frequency. Six colored LEDs of different emission wavelengths with integrated series resistor mounted on carrier plate with shaft. Wavelengths: 465 nm, 560 nm, 585 nm, 635 nm, 660 nm, 950 nm Series resistor: 100 Ω, 1% Voltage: max. 6 V Dimensions: 115x115 mm Weight: approx. 120 g