Demonstration of the Phenomenon of Scattering of Light

What You Need to Know

Scattering is the deflection or the spreading out of light as it passes through material.

How Does Scattering Work?

Scattering is different from refraction. Refracted light is deflected in only one direction. Scattering means the light is deflected in all directions. Scattering happens when light energy is absorbed by a particle or a molecule and causes the electrons to be more energized. When the electrons release this extra energy it is in the form of light energy. The released light energy is scattered. Selective scattering occurs when certain particles are more effective at scattering a particular wavelength of light. If particles are small, short-wavelength light is scattered more than long-wavelength light.

What Does This Have to Do with Demonstrating the Scattering of Light?

Some particles and molecules found in the atmosphere have the ability to scatter sunlight. Air molecules, like oxygen and nitrogen, for example, are small in size and thus more effective at scattering shorter wavelengths of light than are large molecules. The shortest wavelengths of visible light are the colors blue and violet. The scattering of sunlight by air molecules is responsible for producing blue skies. The diagram shows the scattering of blue light in all directions by oxygen molecules.

Real-Life Science Challenge

Light passing from space through Earth's atmosphere is scattered. Because this light is scattered, it is difficult for scientists using telescopes on Earth to see objects in space. The primary reason for placing the Hubble space telescope in orbit around Earth was to eliminate this undesirable effect of Earth's atmosphere.

Experiment

Now, start experimenting with light scattering.

Hints

• A penlight or other light with a narrow light beam works best as a light source.
• Investigate Raleigh Scattering experiments, then design a liquid solution to simulate particles in air. Try using small drops of milk or dishwashing soap in water.
• Design a way to create a screen to observe the color of light that is not scattered but passes through the solution.

Fun Fact

Over the ocean, the scattering of light by salt particles suspended in the air causes brilliant red sunsets. The color is most intense when the sun is closest to the ocean surface because the light passes through more air, and more of the shorter wavelengths are scattered. Red has the longest wavelength so it is not scattered, and more of the red light reaches your eye.

This article is brought to you by:

From this Book:

Janice VanCleave's Super Science Challenges: Hands-On Inquiry Projects for Schools, Science Fairs, or Just Plain Fun!
Buy this book »