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Determining Planck's Constant with LEDs: Investigating the Photoelectric Effect and Electronic Light Sensors Kit


Product: (in stock)


Grades 9–12. In 3 experiments, students determine the wavelength of 4 LED colors and construct a circuit to find the threshold voltage of the LEDs. This is used to calculate frequency and energy, and to generate a mathematical model for Planck's constant.

PE: HS-PS4-3
Related PE: HS-PS3-3
Time Requirement: 90 minutes

SEP: Using Mathematics and Computational Thinking
CCC: Systems and System Models
DCI: HS-PS4.B Electromagnetic Radiation

Take a smartphone selfie, walk through an automatic door, or turn on your television with a remote, and you're using light sensors based on the photoelectric effect. In this comprehensive kit students:

  • Investigate light sensors and the photelectric effect
  • Build circuits to determine Planck's constant
  • Learn how light-emitting diodes (LEDs) and transistors function

Students establish relationships among light frequency, wavelength, and energy for LEDs while collecting data to calculate Planck's constant. Investigate the wave and particle models of light as students calculate threshold voltages to turn on LEDs (photoelectric effect) and calculate wavelength using a diffraction grating. The photoelectric effect and the discrete nature of quantum mechanics are addressed, laying the foundation for this lab.

Activities are designed for 4 groups working in 4 student teams. FREE 1-year access to digital resources that support 3-dimensional instruction for NGSS included.

The activities in this kit build toward the following Performance Expectations of the Next Generation Science Standards*: HS-PS4-3, HS-PS3-3. This kit is designed to integrate into a larger unit of lessons addressing wave mechanics, electricity, magnetism, and electromagnetism.

*Next Generation Science Standards® is a registered trademark of WestEd. Neither WestEd nor the lead states and partners that developed the Next Generation Science Standards were involved in the production of this product, and do not endorse it.


What’s Included:
  • Mini Breadboards
  • 5 LEDs, Red
  • 4 LEDs, Yellow
  • 4 LEDs, Green
  • 4 LEDs, Blue
  • 1 LED, Infrared
  • 1 Hookup Wire (22 AWG), 100-ft Roll
  • 1 Resistor, Light-Dependent
  • 1 Resistor, 10 kOhm
  • 1 Resistor, 100 kOhm
  • 1 Resistor, 330 Ohm
  • 1 Resistor, 470 Ohm
  • 4 Resistors, 100 Ohm
  • 2 Transistors, 2N3904
  • 4 Potentiometers, 1 kOhm
  • Diffraction Gratings
  • 12 D-Cell Battery Holders
  • 30 Alligator Clip Leads
  • 1 Carolina Science Online® Resources (1-year subscription)
  • 1 Teacher's Manual with Reproducible Student Guide
  • expand to see full list
What's Excluded:
Return Policy:

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