What Is Color? | Physics in Motion

Summary

This segment of 'Physics in Motion' delves into the science of color, explaining how objects absorb and reflect light to produce the visible spectrum. It distinguishes between the primary colors of pigments and light, and demonstrates how mixing these can create white light. The video also explores the concepts of additive and subtractive color mixing, the role of chlorophyll in plant photosynthesis, and how our eyes perceive color through rods and cones. It highlights the importance of color in nature for signaling and disguise, and its enhancement of our visual world.

Takeaways

• 🌈 Color is a part of the electromagnetic spectrum that we can see, known as the visible spectrum.
• 🎨 Objects appear colored because they absorb some wavelengths of light and reflect others that we perceive.
• 🔍 The visible spectrum ranges from violet to red, with each color having a specific wavelength.
• 🚫 Infrared is just beyond the red end of the visible spectrum, and ultraviolet is beyond violet.
• 👀 Human eyes can perceive wavelengths from approximately 390 to 790 nanometers.
• 🌟 It's estimated that humans can distinguish between 18 decillion colors.
• 🟥 The primary colors of light are red, green, and blue, which combine to form white light.
• 🌿 Leaves appear green because they reflect green light and absorb other colors, facilitated by chlorophyll.
• 🖼️ Additive color mixing involves combining light wavelengths to create various colors, including white when all primary colors are combined.
• 🖌️ Subtractive color mixing occurs with pigments or dyes, where some wavelengths are absorbed and others reflected, creating color.
• 👁️‍🗨️ Our eyes contain rods and cones that detect light and color, with cones being responsible for color perception.

Q & A

What is color in the context of the electromagnetic spectrum?

Color is the part of the electromagnetic spectrum that we can see, known as the visible spectrum.

How do objects appear to have different colors?

Objects appear to have different colors because they absorb some wavelengths of light and reflect others. The colors we see are those wavelengths that are not absorbed and are reflected back to our eyes.

What is the range of wavelengths that correspond to the colors we can see?

The spectrum of color ranges from violet to red, with each color having a specific wavelength. Red has the longest wavelength and violet the shortest.

What is the approximate range of wavelengths that human sight can perceive?

Human sight can perceive wavelengths from about 390 to 790 nanometers.

How many colors are estimated to exist in the universe that we can distinguish?

It's been estimated that we can distinguish between 18 decillion colors.

What are the primary colors of light, and what happens when they are mixed?

The primary colors of light are red, green, and blue. When mixed in equal intensities, they produce white light.

What is the difference between the primary colors of pigments and the primary colors of light?

The primary colors of pigments are red, blue, and yellow, while the primary colors of light are red, green, and blue. This difference is due to how pigments absorb and reflect light differently than how light itself combines.

Why does a leaf appear green?

A leaf appears green because it reflects the wavelength of green light and absorbs all the other colors. This is due to the presence of chlorophyll, which is involved in photosynthesis.

What is luminance and how is it measured?

Luminance is the measure of brightness of a surface, measured in candelas per square meter. It is the amount of light reflected off a surface.

How is the color white light produced through additive color mixing?

White light is produced through additive color mixing when the primary colors of light (red, green, and blue) are overlapped in equal intensities.

What is the difference between additive and subtractive color mixing?

Additive color mixing involves combining light of different wavelengths to create colors, while subtractive color mixing involves pigments or dyes that absorb certain wavelengths and reflect others, creating colors by subtraction.

How do our eyes perceive color?

Our eyes perceive color through rods and cones, which are photoreceptor nerve cells. Cones are responsible for color perception, while rods are more sensitive to light but not to color.