Physics Chapter 28 Flashcards

Questions and Answers

List the order of the colors in the color spectrum.

Red, Orange, Yellow

Green, Blue, Indigo, Violet

All of the above

Red, Orange, Yellow, Green, Blue, Indigo, Violet (correct)

Are black and white real colors in the sense that red and green are? Explain.

No, black is the absence of light and white is a mixture of all the colors.

What is emitted by the vibrating electrons of atoms?

Electromagnetic waves.

What happens to light of a certain frequency that encounters atoms of the same resonant frequency?

The light is absorbed. Signup and view all the answers

Why does the color of an object look different under a fluorescent lamp from the way it looks under an incandescent lamp?

Fluorescent light is rich in the higher visible frequencies and has a blue cast to it, while incandescent light is rich in the lower frequencies. Signup and view all the answers

What colors of light does a transparent red object transmit?

Red light. Signup and view all the answers

What color(s) does it absorb?

All the colors except red. Signup and view all the answers

What is the function of a pigment?

Pigments absorb certain frequencies/colors of light. Signup and view all the answers

Why are more and more fire engines being painted yellow-green instead of red?

The human eye is most sensitive to yellow-green and sees it as the brightest color. Signup and view all the answers

How can yellow be produced on a screen if only red light and green light are available?

Red and green light can be mixed together to form yellow light. Signup and view all the answers

What is the name of the color produced by a mixture of green and blue light?

Cyan. Signup and view all the answers

What colors of spots are lit on a television tube to give full color?

Red, Green, and Blue. Signup and view all the answers

What are complementary colors?

Two colors of light that when added together produce white. Signup and view all the answers

What color is the complement of blue?

Yellow. Signup and view all the answers

Why do we say 'subtraction' instead of 'addition' in the case of pigments?

Each pigment absorbs or subtracts colors from the incident light. Signup and view all the answers

What colors of ink are used to print full-color pictures in books and magazines?

Cyan, Yellow, Magenta, and Black. Signup and view all the answers

What is light scattering?

The absorption and reemittance of light in all directions. Signup and view all the answers

Why is the sky blue?

The sky is blue because tiny particles in the atmosphere scatter mostly violet and blue light. Signup and view all the answers

Why are clouds white?

Droplets in clouds scatter light of different sizes, covering the spectrum and producing white. Signup and view all the answers

Why are sunsets red?

The red end of the visible spectrum is scattered least, leaving only red light. Signup and view all the answers

Why is water greenish-blue?

Water absorbs infrared and visible red light, leaving the blue end of the spectrum. Signup and view all the answers

Does the red light from glowing neon gas have only one frequency or a mixture of frequencies?

Neon gas gives off light of several, discrete frequencies. Signup and view all the answers

Why might atomic spectra be considered the fingerprints of atoms?

Each element gives off a distinct set of spectral lines that is unique to that element. Signup and view all the answers

Study Notes

Color Spectrum

The order of colors in the visible spectrum is red, orange, yellow, green, blue, indigo, and violet.
Black is the absence of light, while white is a combination of all colors.

Properties of Light

Vibrating electrons in atoms emit electromagnetic waves (light).
Light of a specific frequency that encounters atoms of the same resonant frequency is absorbed.

Light Sources

Fluorescent lamps emit more high-frequency (blue) light whereas incandescent lamps emit more low-frequency (red) light, affecting how colors appear under different lighting.

Color Transmission and Absorption

A transparent red object transmits red light and absorbs all other colors.
Pigments selectively absorb specific light frequencies and reflect others, providing their color.

Color Sensitivity

Human sensitivity to color is highest for yellow-green, leading to its use in fire engine paint for visibility.

Color Mixing and Production

Yellow can be produced by mixing red and green light in equal parts.
Cyan is the result of mixing green and blue light.

Television Color Production

Full color on a television screen is produced using red, green, and blue light, known as additive primary colors.
Complementary colors are pairs of colors that, when combined, produce white light (e.g., blue and yellow).

Pigments and Subtractive Color Mixing

The pigment mixing process is called subtraction because it absorbs (subtracts) certain colors from white light, rather than adding to it.
Cyan, magenta, yellow, and black inks are used in printing to create a full spectrum of colors.

Scattering of Light

Light scattering occurs when light is absorbed and re-emitted in multiple directions.
Tiny particles scatter high frequencies of light while large particles scatter low frequencies, affecting atmospheric color perception.

Atmospheric Effects on Color

The blue color of the sky results from the scattering of blue and violet light by air molecules; eyes are less sensitive to violet, making the sky appear blue.
Whitish skies may occur due to larger particles like dust scattering lower frequencies.
Clouds appear white because of varying droplet sizes scattering light across the spectrum.

Sunsets and Water Color

Sunsets appear red as blue and violet light is scattered more, allowing primarily red light to reach our eyes.
Water appears greenish-blue due to the absorption of red light, resulting in the reflection of blue wavelengths.

Spectroscopy

A spectroscope is used to separate light into its constituent frequencies, revealing distinct lines for different elements—considered atomic "fingerprints."
Neon gas emits light at several discrete frequencies, contributing to its characteristic glow.

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Description

Test your knowledge of colors and light in Physics Chapter 28 with these flashcards. Each card presents key concepts about the color spectrum and the nature of light. Perfect for reviewing essential principles in physics!