GUEST BLOGGER HENRY HERZ
Told in lyrical, riddling first-person narrative, Light boasts of its essential role in life as we know it. Back matter about the science of light and major historical discoveries enhances STEM learning.
Amazing light facts
- Light weighs nothing and can travel as fast as 186,000 miles per second or about 671 million miles per hour. In a year, light travels 5.9 trillion miles. That’s called a light-year.
- Visible light is part of a broader range of electromagnetic radiation that includes radio waves, microwaves, infrared radiation, ultraviolet (UV) light, x-rays, and gamma rays. Some animals can see UV light, including butterflies, reindeer, some birds, bees, sockeye salmon, and hedgehogs.
- Photovoltaic cells convert light into electricity
- Without the sun’s light (and heat, aka infrared radiation), life would not be possible on Earth. Plants, cyanobacteria, and algae need light to grow. Many animals need algae or plants to grow.
- Plants use light to convert carbon dioxide and water into sugar and oxygen, which is how they grow. This is called photosynthesis.
- Plants bend toward sources of light. This is called phototropism.
- Some plants and animals, like fireflies and anglerfish, make their own light using chemicals inside their bodies. This is called bioluminescence.
(bioluminescence image)
- Sometimes, light behaves like a wave. Other times, it behaves like a particle.
- Visible light is comprised of the colors red, orange, yellow, green, blue, indigo, and violet. Everything you see is because some colors are absorbed, while the others are reflected.
- When light passes between two different materials, it bends or refracts. Rainbows are made from light refracted by water droplets.
(refraction image) - Convex lenses squeeze light tighter for microscopes and telescopes. Concave lenses spread light out for movie projectors.
- If we view a star that is one million light-years away, that means we’re seeing light that left the star one million years ago. So telescopes let us look into the past.
Fun with light: Convex lenses
Objective
Observe how convex lenses concentrate light.
Materials
- balloon
- tape
- magnifying glass
Demo
Inflate the balloon. Go outside on a sunny day and tape the balloon to the ground so it won’t blow away. Explain that the convex lens of a magnifying glass concentrates the light energy into a small point as you use it to burst the balloon.
Fun with light: Refraction
Objective
Observe how water refracts light.
Materials
- glass half full of water
- pencil
- bowl
- coin
- clear 64-ounce soda bottle with label removed
- sheet of paper
- pen
Demo
- Experiment 1: Place the pencil in the glass and note how refraction causes the pencil to appear broken.
- Experiment 2: Place the coin in the bowl such that the coin is not visible when viewed from a certain angle. Then, fill the bowl with water and note how refraction now makes the coin visible from the same viewing angle.
- Experiment 3: In the center of the paper, draw an arrow pointing right. Fill the bottle with water and hold the paper right behind the bottle. Slowly move the paper away from the bottle to observe how the arrow seems to flip direction when viewed through the bottle.
Fun with light: Color spectrum
Objective
Observe how visible light is comprised of all the colors and how different colors absorb differing amounts of light energy.
Materials
- a triangular glass prism
- Infrared thermometer
- Sheets of red, blue, white, and black paper
Demo
Hold the prism in sunlight and note how a rainbow of colors is made as refraction splits white light into its component colors: red, orange, yellow, green, blue, indigo, violet.
Next, set the sheets of paper in full sunlight (hold in place with rocks on the corners). After a few minutes, measure the temperature of the paper surfaces and note how the temperature varies from hottest to coolest (black, red, blue, white).
Featured image credit: “Mini light bulbs” by Andrew.T@NN is licensed under CC BY-NC-SA 2.0.
Henry Herz is the author of fourteen picture books, including I Am Gravity and the award-winning I Am Smoke. Find him at henryherz.com, https://www.facebook.com/henryherzauthor, https://www.instagram.com/henry_herz/, and https://bsky.app/profile/henryherz.bsky.social
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