Vernier Software & Technology

# Planck’s Constant

## 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.

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

## Advanced Physics with Vernier — Beyond Mechanics

See other experiments from the lab book.

 1 Behavior of a Gas 2 Heat Engines 3 Standing Waves on a String 4 Standing Waves in a Column of Air 5 Doppler Effect 6 Electrostatics 7 Coulomb's Law 8 Mapping Electric Potential 9 Factors Affecting Electrical Resistance 10 Series and Parallel Circuits 11 Faraday’s Law: Moving Magnet 12 Faraday’s Law: Alternating Current 13 Capacitors and Inductors 14 RLC Circuits 15 Curved Mirrors and Images 16 Thin Lenses and Real Images 17 Thin Lenses and Virtual Images 18 Aperture and Depth of Field 19 Interference 20 Diffraction 21 Spectrum of Atomic Hydrogen 22 Planck’s Constant

### Experiment 22 from Advanced Physics with Vernier — Beyond Mechanics Lab Book

#### Included in the Lab Book

Vernier lab books include word-processing files of the student instructions, essential teacher information, suggested answers, sample data and graphs, and more.