Sunset Demonstration

This demonstration shows why sunsets appear red in the sky. As the sun sets, it is lower in the sky and thus the white light from it has to travel through more of the atmosphere before it reaches our eyes. The light encounters more particles in the atmosphere so more of the higher frequency, shorter wavelength light is scattered away. This leaves the lower frequency, longer wavelength red light to reach our eyes.

* Equipment seen in the video may vary from equipment used in ND Demonstrations. See information and images below for ND equipment and setup.

Setup:

Place the fish tank on the demo table. Place the lamp on a board on one end and the white screen on the other end of the tank. Place the lens between the tank and the lamp.

Turn on the lamp and adjust the height of the lens and screen so that the light passes through the lens and the tank, and is visible on the screen. Turn off the lamp.

Fill the tank with water so that the entire light beam passes through the water.

In the beaker, mix coffee creamer with water until there are no chunks.

Turn on the lamp and slowly add the creamer mixture to the tank. Stir to combine. Repeat this process, watching as the image on the screen turns yellow, then orange, then red. Eventually the light will not be able to pass through the tank.

Notes:

This is best done with the lights down or off.

This can also be done with Pine Sol but the correct ratio is more difficult to get.

Courses Used In:

Coming Soon

Discussion and Polling Questions:

Coming Soon

Equipment Needed:

• Fish Tank

• Water

• Coffee Creamer

• 250 W Lamp Sitting on Board to Raise the Height

• 500 mm Lens with Stand

• White Screen

• Beaker

• Wooden Spoon