Physics Lab Equipment

LEAI-50 Apparatus for Determining Planck's Constant - Basic Model

LEAI-50 Apparatus for Determining Planck's Constant - Basic Model


  • Complete apparatus

  • Compact and stable

  • Low dark current

  • Affordable


This LEAI-50 Experiment Apparatus of Planck's Constant is used to demonstrate photoelectric effect and calculate Planck’s constant according to Einstein’s equation of photoelectric effect. It is a cost-effective teaching apparatus for physics laboratories at colleges and universities. The instruction manual contains experimental configurations, principles and step-by-step instructions. Please click Experiment Theory and Contents to find more information about this apparatus.


Cut-off wavelengths of color filters635 nm, 570 nm, 540 nm, 500 nm, 460 nm
Light source12 V/35 W Halogen Tungsten lamp
Sensorvacuum phototube
Dark-currentless than 0.003 µA
Precision of accelerating voltageless than ± 2%
Measurement errorapproximately ± 10% as compared with literature value

Parts List

Main unit1
Power cord1
Instruction manual1

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Schematic diagram of apparatus

1 Light source, 2 Base rail, 3 Scale, 4 Receiver cover (or filter), 5 Receiver tube, 6 Focusing lens, 7 Vacuum phototube, 8 Receiver box, 9 Digital meter (V or I), 10 Display mode switch (V or I), 11 Current multiplier, 12 Light intensity adjust, 13  Accelerating voltage adjust, 14 Voltage polarity switch, 15 Power switch, 16 Power indicator, 17 Lock screw

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