The Color of Quantum
Aron Fristoe, Educator, MathScience Innovation Center
Developed with funding from the MathScience Innovation Center
Adapted from the “LED Color Strip Kit” available through the Institute of
Chemical Education http://ice.chem.wisc.edu/
Major
Understanding
Classical Newtonian Physics describes the behavior and motion of matter at
the macroscale. As the size of matter becomes smaller and transitions into the
nanoscale, predictions of properties based on classical physics begin to fail and
quantum mechanics must be used to predict and explain the behavior of matter.
At the heart of quantum mechanics is the concept of the particle-wave duality
of matter which states that all matter exhibits either wave-like or particle like
properties depending on the methods used to observe them. For matter at the
nanoscale, wave character becomes more important. In addition, quantum
systems at the atomic and subatomic scale can only allow energy of certain
discrete amounts to enter or exit. When this occurs, the energy levels are
considered to be quantized. In this lesson, students will use LED light strips to
explore the science and math behind quantum effects and discover Planck’s
Constant.
Grade/Subject
Physical Science, Chemistry and Physics
Objectives
Explain light is caused by the release of photons when electrons
move from ground to excited state and back to ground state.
Measure wavelengths of light and the voltage needed to light an
LED.
Calculate and explain the relationships between wavelength,
frequency and energy.
Calculate and use Planck’s constant.
Time
Anticipatory Set: What causes light?
Activity: Get to Know Your LED Kit
Demonstration: Viewing Gas Discharge Tubes
Demonstration: What are Waves?
Activity: Measuring the wavelengths of light Activity:
Activity: Finding Voltage and Crunching the Numbers
Closure: Periodic Properties and LED lights
Practice Assessment
10 min
10 min
10 min
5 min
20 min
20 min
10 min
Variable
Materials
For the class:
Computer
Projector
PowerPoint
Gas discharge tubes and power supply
Hydrogen is needed and additional tubes can be used.
Graphing calculators
For each group of students working in pairs (up to 30)
LED light strip (available from the Institute of Chemical Education)
9 volt battery
Clipboard
Three ¼” Binder Clips
Christmas Tree light bulb with wire leads exposed
500 lines/mm linear diffraction grating (available from Rainbow Symphony)
Vernier LabQuest and voltage probe or other voltage meter
State and National
Correlations
Instructional
Strategies
Virginia Standards of Learning: Physical Science (PS.3, PS.9); Chemistry
(CH.2, CH.6); Physics (PH. 9, PH.12)
National Science Education Standards: Physical Science: Structure of Atoms
1. Anticipatory Set: What Causes Light? (Slides 1-5)

Introduce the nature of light with the video “What the Heck is
Light” which is linked on Slide 3.

Use slides 4 & 5 to discuss the Quantum model of the atom.

Introduction to the properties of light and relationship to the
quantum model of the atom
2. Activity: Inquiry Based Investigation on LED Lights using the
LED Color Strip (Slide 6)

Have students use the LED Color Strip, 9 Volt Battery,
incandescent Christmas tree light bulb, and a digital camera
(cell phone cameras are adequate) to complete the questions to
the “Getting to Know Your LED Kit” Activity Sheet.

Student Data Sheet; Student Data Sheet Key

The digital camera/cell phone camera is for viewing the InfraRed LED. Not all cameras will be able to see the light emitted.
Using a web-cam is a nice way to demonstrate this to the whole
class.

Main Idea: Differentiate between LED and incandescent light;
differentiate between IR and visible light. Examine a diode.
3. Demonstration Using Gas Discharge Tubes (Slides 7-10)

Turn on the hydrogen discharge tube and have students look
through the diffraction slides to view the emission spectra
pattern. A dark room will allow the best viewing opportunity.
Students may have to move closer to the discharge tubes to see
the emissions spectra. Leave slide 7 up on the screen so the
students can see the pattern they are looking for.

Repeat with the remaining gas discharge tubes.

Use slides 8-10 to summarize how Bohr used the emissions
spectra to determine electrons are found in energy levels and
how different types of light fixtures use excited light to emit
light.
4. Demonstration: What are waves? (Slides 11-12)

Use Slide 11 to discuss the Electromagnetic Spectrum and
introduce wavelength and frequency

Use the Wave Applet linked at Slide 12 to demonstrate the
properties of waves.
5. Activity: Measuring Wavelengths of Light (Slides 13-14)

Slide 14 shows the recommended set up.

Have students follow the directions and complete the questions
on the Student Activity Sheet.

Main Idea: Explore the relationship between color and
wavelength of that particular color.
6. Activity: Finding Voltage and Crunching the Numbers (Slide 15)

Have students follow the directions and complete the questions
on the Student Activity Sheet.

Main Idea: Understand Planck’s constant and the linear
relationships between wavelength, frequency, and energy.
7. Closure: Periodic Properties (Slides 16-24)



Prior to discussing the results of the last activity, discuss how
LED lights work using Slides 16-22. Stress that knowing
Periodic Properties such as atomic radius and number of
valence electrons determine the wavelength of light that is
produced. Point out that “Band Gap” energy is a special type of
ionization energy and is similar to the atomic emissions spectra
observed earlier in the lesson. The energy of the bond
determines the wavelength of light.
Use Slide 23 to review possible answers to the last activity.
Use Slide 24 to discuss Planck’s constant its relevance.
Extensions
1. Have the students research LED lights and what combinations of
elements will give different colored lights.
2. Have the students design a lab on the efficiency of LED lights.
Assessment
Sample items are provided for use in the checking students’ understanding.
Paper/Pencil Assessment: The Color Of Quantum
Paper/Pencil Assessment Key
Project and Rubric
The following table shows how the assessment items are related to specific
objectives.
Objective
Paper-Pencil Test
Students will understand that
2
light is caused by the release
of photons when electrons
move from ground to excited
state and back to ground state.
Measure wavelengths of light
5, 7
and the voltage needed to
light an LED
Calculate and explain the
3, 4, 6
relationships between
wavelength, frequency and
energy.
Use Planck’s Constant
1
Major understanding
Product/Performance
Activity 1: LED strip
Activity 2:
Measurement of
wavelengths.
Activity 2:
Measurement of
wavelengths.
Activity 2: Analyze
calculated relationship
between energy and
frequency.
Project and Student
Rubric
Teaching Tips
This lesson was adapted from the “LED Color Strip Kit” available at the
Institute of Chemical Education http://ice.chem.wisc.edu/ LED light strips may
be purchased from ICE and the LED Color Strip Kit manual provides many
additional activities and information on where to purchase additional supplies.
Supplies
Institute for Chemical Education (ICE)
ICE provides many resources for teaching nanoscience across the science
curriculum. http://ice.chem.wisc.edu/
Rainbow Symphony
Rainbow Symphony carries a variety of diffraction gradients and other light
related products. http://www.rainbowsymphony.com/
References
Institute for Chemical Education (ICE)
ICE provides many resources for teaching nanoscience across the science
curriculum. http://ice.chem.wisc.edu/
MathScience Innovation Center
Information on educational programs available to students, teachers, and
school divisions as well as procedures for registering for programs.
http://msinnovation.info
MathinScience:
Find resources which teach core math and science standards, integrate
calculator and computer-based technologies, and introduce 21st Century
concepts in the areas of fractal geometry, nanotechnology, and engineering.
http://mathinscience.info
Recommended
reading
Orzel, Chad. How To Teach Physics To Your Dog. New York: Scribner, 2010.
Kakalios, James. The Amazing Story Of Quantum Mechanics, A Math-free
Exploration Of The Science That Made Our World. New York: Gotham, 2011