# Why Does an Apple Look Red?

## Presentation on theme: "Why Does an Apple Look Red?"— Presentation transcript:

Why Does an Apple Look Red?

What color of light does a red filter allow to pass through to your eyes?

Where is the light coming from in this room?
The inside of a fluorescent light bulb is coated with a material that glows when energized. The bulb contains mercury vapor. This gas absorbs* energy* from the electricity* that passes through the bulb. This electrified gas emits ultraviolet light, which energizes the chemical, causing it to glow. Fluorescent light bulbs come in a variety of shapes.

Use the diffraction grating and look at the room lights.
What colors do you see?

If the light that fills this room is composed of many different colors, why is it that objects illuminated by these lights seem to be only certain colors? Record your answer

Draw this diagram on your paper

Our eyes and our brains interpret light of different wavelengths as different colors.

Now we will connect some of these ideas together.
Can you explain why a green sheet of paper looks green? The starting point for your explanation should be the light coming from the light bulb.

The paper appears green because the green light reflects from it
The paper appears green because the green light reflects from it. What happens to the other colors of light? Eye All colors from light bulb Green paper absorbs all colors except green.

View this green rectangle with the red and green filters and record what you see.

Can you explain the results you observed for the red filter?
Eye All colors from light bulb Green light is stopped by red filter, thus the paper looks dark.

In other words, how we were able
We will now pause the show and reflect on which colors go through a red filter and which colors are stopped. In other words, how we were able make secret messages.

Now see if you can predict how a rectangle of red will appear through the red and green filters.
The rectangle is light red through red filter and dark through the green filter.

Now see if you can predict how black and white will look through the red and green filters.
White looks red through red filter and green through the green filter. Black still looks black through both filters.

What colors reflect off white and black surfaces?
All colors reflect off white. All colors are absorbed by black, thus no colors reflect off black.

How will red and white stripes appear through the red filter?
The red stripes appear to disappear. Can you explain why?