Planck’s Constant
Recommended for grades 11–16.
Introduction
The energy of a photon is related to its frequency by the equation E = hf, where h is Planck’s constant. By determining the potential required to excite an LED to emit light, you can estimate the energy of the photons emitted. Using a spectrometer, you can measure the peak wavelength of the emitted light; from this, the frequency can be calculated. Performing this analysis for a number of LEDs will enable you to obtain a reasonable approximation of the value of Planck’s constant.
Objectives
In this experiment, you will
- Collect and analyze current vs. potential data to estimate the energy required to excite a number of LEDs.
- Use a spectrometer to determine the wavelength of the peak output of each LED.
- Determine a value for Planck’s constant from an analysis of the energy and frequency of the light emitted by a number of LEDs.
Sensors and Equipment
This experiment requires each of the following Vernier sensors and equipment (unless otherwise noted):
Additional Requirements
You may also need an interface and software for data collection. What do I need for data collection?
Download Experiment Preview
The student-version preview includes:
- Step-by-step instructions for computer-based data collection
- List of materials and equipment
Note: The experiment preview of the computer edition does not include essential teacher information, safety tips, or sample data. Instructions for Logger Pro and other software (such as LabQuest App or TI handheld software, where available) are on the CD that accompanies the book. We strongly recommend that you purchase the book before performing experiments.
Standards Correlations
No standards correlations for this experiment.
Experiment 22 from Advanced Physics with Vernier - Beyond Mechanics Lab Book
Included in the Lab Book
Vernier lab books include a CD with word-processing files of the student instructions, essential teacher information, suggested answers, sample data and graphs, and more.