Light Emitting Diodes (LED)

A CIPT Lab Exercise in Modern Physics

Abstract

Light emitting diodes (LEDs) are increasingly being used as indicators in electronic devices and as efficient light sources such as traffic lights.  Using super-bright LEDs, students investigate the conversion of electrical energy into light and vice versa.  By measuring and comparing the energy lost by each electron with the frequency of the emitted light for several LED colors students estimate Plank's constant, a fundamental number of quantum mechanics.

Appropriate Levels

Regents Physics, Engineering

Time Required

Two 45-minute class periods.

Materials

Light Emitting Diodes is a kit available from the CIPT 
Equipment Lending Library, www.cns.cornell.edu/cipt/. It is 
also available commercially from West Hill Biological 
Resources, Inc.

 
Copyright for this material is held by Cornell University, the Cornell Institute for Biology Teachers (CIBT), the Center for Nanoscale Systems Institute for Physics Teachers (CIPT), and or West Hill Biological Resources, Inc., 2014. This work may be copied by the original recipient from this web site to provide copies for users working under the direct supervision of the original recipient. All other redistribution of this content without the express written permission of the copyright holder(s) is prohibited.

Price: No Charge

Authors:
Preeti Chalsani
Ralph Greco