Measuring Planck's Constant

Students use a simple circuit and LEDs to measure Planck's constant, h, a universal constant that lies at the heart of quantum mechanics, to within an error of 20%.


  • Lesson plans: Measuring Planck's Constant
  • Activities: Scientific Models: Time; Scientific Revolution: Special Relativity (worksheets, review questions, and solutions)
  • Supplementary Materials: Teacher's notes, The Physics Behind LEDs, and more
  • Teacher-provided Materials: Voltmeter, 5 LEDs of different frequencies, 6V or 9V cell, 1 kilo-ohm potentiometer, 330 ohm resistor, voltmeter, 5 connecting wires, graph paper

(Note: all lesson plans and worksheets provided as PDFs and modifiable MS Word documents)

Intended Audience: Senior High (Gr 11-12)
Lesson Topics: Energy, Planck's Constant, Quantum, Relativity
Price: Free