# Planck’s Constant

Recommended for High School through College.

## 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 features the following Vernier sensors and equipment.

### Additional Requirements

You may also need an interface and software for data collection. What do I need for data collection?

## Standards Correlations

No standards correlations for this experiment.