Lessons in Light: Exploring the Electromagnetic Spectrum


Lessons in Light Exploring

This lesson was created by Michael Wilkinson, Fieldston Lower School in Bronx, NY and his 4th and 5th grade students.

What is light?

Light is energy. It is vital to life. It is part of what we call the electromagnetic spectrum. We all know the spectrum of (visible) light as the rainbow: red, orange, yellow, green, blue and violet. There is so much more to the spectrum beyond what our eyes can perceive, including Infrared, radio waves, microwaves, x-rays, gamma rays and ultraviolet.

Light Labs

littleBits make it easy to experiment with light. Experimental apparatus can be prototyped in a few minutes and students can begin collecting data immediately.

For each lab group, you will need one set of the listed modules, accessories, and supplies.

Objectives:

Students will be able to:

– Use littleBits to explore the visible light spectrum

– Understand how our eyes and brains interpret color

– Extend learning by investigating other types of light waves in the electromagnetic spectrum

Assessment:

Throughout the lesson, consider using some of the following assessment techniques:

– Observe students as they work with littleBits modules

– Ask questions to individuals and groups to check for understanding

– Gather student questions for further inquiry

– Collect exit tickets at the conclusion of the lesson to document learning

Standards:

NGSS Disciplinary Core Ideas

– PS3: Energy

Check out these websites for more on the Electromagnetic Spectrum:

– Tour of the Electromagnetic Spectrum: http://missionscience.nasa.gov/ems/

– Imagine the Universe: Electromagnetic Spectrum:

– Part 1: http://imagine.gsfc.nasa.gov/docs/science/know_l1/emspectrum.html

– Part 2: http://imagine.gsfc.nasa.gov/docs/science/know_l2/emspectrum.html

– Mission Science: Introduction to the Electromagnetic Spectrum: http://science.hq.nasa.gov/kids/imagers//ems/index.html

– Tour of the Electromagnetic Spectrum (Video): http://m.youtube.com/watch?autoplay=1&v=HPcAWNlVl-8

Duration: 2 days of 45-minute classes

GRADE LEVEL
Elementary (ages 8-10)
Middle School (ages 11-13)

DIFFICULTY
Intermediate

SUBJECT
Science

MODULES & ACCESSORIES USED (18)
light sensor (1)
bargraph (1)
led (1)
uv led (1)
power (1)
rgb led (6)
fork (1)
bright led (1)
synth speaker (1)
mounting boards (1)
IR LED (1)
number (1)
battery + cable (1)

OTHER MATERIALS USED (5)
spectroscope or diffraction grating glasses 1
prisms 1
cardboard 1
Tape 1
Glue 1

TOOLS USED
Scissors
screwdriver

LESSON GUIDE

STEP 1 : Introduction: RGB Lab

Through this investigation, students will explore how the human retina responds to the varying combinations of red, green and blue light to produce all of the colors of the visible light spectrum.

Each group will design a “variable flashlight” using the RGB LED Bit modules. Students should be encouraged to experiment and figure out for themselves how the circuits should be built.

STEP 2 : Build the Circuit

Lessons in Light Exploring1

Essentially, the circuit would be:

battery + power + RGB LEDs

Secure the circuits to mounting boards to make it easier to work with them. Each group will need a littleBits screwdriver to “tune” the RGB LED through the spectrum.

You can begin by handing out one RGB module per group and build this 6 RGB chain together as a class for visual effect.

STEP 3 : Issue the Challenges

Can all of the colors of the visible light spectrum be produced with the RGB LED bit module? (Red, Orange, Yellow, Green, Blue and Violet)

Can “white light” be produced with the RGB LED bit?

What combinations of Red, Green and Blue are needed to produce each of the colors of the spectrum? What is the “recipe” for each color of light?

STEP 4 : Examine the Spectrum

Lessons in Light Exploring2

If spectroscopes or diffraction grating glasses are available, have students compare the spectra of each color of light produced by the RGB LEDs.

STEP 5 : Conclusions

Lessons in Light Exploring

Just as blending different intensities of Red, Green and Blue light produces different colors of light emitted from the LED, the Red, Green and Blue cones on the retina of our eyes are being stimulated at different levels. Those signals are sent to the optical center of our brain for processing and inform us what color we are seeing.

Below: “Spectrographs produced by littleBits RGB LED bits as viewed through diffraction grating glasses. Note the differences in the spectra moving left/red to right/violet.”

STEP 6 : Extension: UV/IR Lab

With the addition of the UV and IR LEDs, students can experiment with a wider range of the EM spectrum. Replace the visible light LEDs with the ultraviolet and infrared LEDs and make comparisons to the spectra produced.

The ultraviolet bit module will produce a very small, but visible purple spectra.

The infrared (IR) module will not produce any visible spectra. Does that mean it isn’t emitting any light? How can that be tested?

Many webcams and digital cameras are able to capture the Infrared bit as it is turned on and off.

Using a prism, produce a full spectrum. Place thermometers in the different color bands as well as just outside the red and violet bands. Compare the temperatures of the light using the ambient room temperature as the control. This is exactly how Sir Frederich William Herschel first identified the presence of infrared light in 1800. A year later, Johann Ritter identified the presence of ultraviolet light.

STEP 7 : Extension: Listening to Light

Lessons in Light Exploring3

If you’ve ever heard of radio or X-ray astronomy, you’ve heard about people “listening” to light. The human eye cannot detect these frequencies of the EM spectrum, yet they are being emitted nonetheless. With littleBits modules, it is possible to build a detector that will convert light energy into a sound that is perceptible by the human ear.

Experiment with different colors of visible light produced by the littleBits RGB LED, the Bright LED, the UV LED and the IR LED. How is the sound wave changed by different wavelengths of light? Do different colors of light produce differing values on the number bit?

The possibilities are endless. Give your students the time and space to explore light and ask questions. Using littleBits modules, they will be able to prototype apparatus and solutions that will lead them to a deeper understanding of the nature of light.

You will find several other investigations exploring the electromagnetic spectrum in the littleBits Space Kit.