Pigment Colors and Light

Pigment Colors

• Primary pigment colors are the secondary colors of light, while secondary pigment colors are the primary colors of light.
• When yellow and cyan pigments are mixed, they absorb blue and red light, respectively, forming a green pigment.
• Yellow + Cyan = (red + blue) absorbed + green, resulting in the appearance of green.
• Similarly, mixing yellow and magenta pigments forms a red pigment, while mixing magenta and cyan pigments forms a blue pigment.

Complementary Pigments

• Complementary pigments are two pigments (one primary and one secondary) that combine to absorb all primary colors, resulting in black.
• Yellow and blue are complementary pigments.
• Cyan and red are complementary pigments.
• Magenta and green are complementary pigments.

Polarization of Light

• Polarization is the production of light with a specific pattern of oscillation (vertical, horizontal, or circular).
• Light is an electromagnetic wave consisting of magnetic and electric fields propagating perpendicular to each other.
• Nonpolarized light has an electric field oscillating in random directions, while polarized light has an electric field oscillating in a specific linear direction.

Polarization by Filtering

• A polarizer (filter) has lines representing a polarizing axis.
• Light with an electric field oscillating parallel to the lines passes through, while light with an electric field oscillating perpendicular to the lines is absorbed.

Diffraction

• When a barrier with a large gap (wider than the wavelength) is placed in the path of light waves, they continue in a straight line.
• When a barrier with a gap nearly the same width as the wavelength is placed in the path of light waves, they spread out (diffract).
• Diffraction also occurs when light waves pass a single edge (bending as it passes the edge of the barrier).

Color

• When a narrow beam of light passes through a glass prism, it spreads out into seven colors (spectrum).
• When this spectrum falls on a second prism, the spreading of colors is reversed, and the colors recombine to form white light.
• The spreading of white light into seven colors when passing through a prism is due to the wave nature of light (different wavelengths bend at different angles).

Color by Addition of Light

• White light can be formed from colored light when the correct intensities of red, blue, and green light are projected on a white screen (additive color process).
• Primary colors are red, blue, and green light, which combine to form white light.
• Primary colors mix to form secondary colors.

Polarization by Reflection

• Light is partially polarized when reflected.
• The light ray is polarized by reflection parallel to the reflecting surface (perpendicular to the reflected ray).
• Polarized reflected light causes glare, which can be reduced using polarizing sunglasses or filters.

Malus's Law

• If a second polarizing filter is placed in the path of polarized light, all light passes through if the polarizing axes are parallel, and no light passes through if the axes are perpendicular.
• Malus's Law states that the intensity of light coming out of the second polarizing filter is equal to the intensity of polarized light multiplied by the cosine squared of the angle between the polarizing axes of the two filters.

Doppler Effect

• The Doppler Effect occurs when there is a relative motion between the source of light and the observer.