NATS 1870 Exam 1 Quiz Prep Questions With Correct Detailed Answers

Hue vs. Color - correct answers Color consists of three dimensions: - Hue, which defines the primary color (e.g., red, green, blue) - Chroma represents the intensity or vividness of a color. - Lightness or value indicates the level of reflectivity, ranging from white to black. Spectral Reflectance Curves - correct answers - Spectral reflectance curves display light reflection percentages across various wavelengths. - These curves are essential for comprehending color perception. - They illustrate how objects absorb and reflect specific wavelengths of light. - This selective absorption and reflection determine the perceived color of objects. Newton's Experiments - correct answers - Newton's experiment used a prism to break white light into a spectrum of colors. - He passed this spectrum through an upside-down prism, recombining the colors into white light. - This experiment showed that white light comprises all colors found in the spectrum. - It proves that white light is a mixture of various colors. 3 types of cones in the eyes - correct answers - L cones: Red - M cones: Green - S cones: Blue Multiple mixing processes - correct answers - Subtractive mixing removes colors when mixing materials like paints. - Additive mixing adds light colors when combining colored lights. - Optical mixing happens within the eye, as in pointillism in art. Mechanics of Vision - correct answers - Photopic vision operates in bright light and relies on cone cells. - Scotopic vision functions in dim light and utilizes rod cells. - Mesopic vision is an intermediate state, combining both rods and cones. Chemistry and Color - correct answers - The pursuit of color has played a crucial role in advancing the field of chemistry. - It has led to the creation of new colorants and dyes. - These innovations have driven important discoveries within the realm of chemistry. Molecular structures that commonly give rise to colour in colourants - correct answers - Conjugated bond: Alternating single and double bonds in a molecule. E.g. Carotenes - found in yellow and orange leaves; carrots. - Auxochromes: Central component of molecule which is colourless - when other atoms/molecules added - a new substance is created which has colour. E.g. azo family, Martius yellow. - Porphyrin: Heavy metal in centre, surrounded by carbon rings. E.g. Chlorophyll, phthalo blue, haemoglobin. - Double covalent bonds - E.g indigo Process of perceiving Color - correct answers - Light from an object enters the eye and interacts with photoreceptors, specifically cones. - Cones are sensitive to various wavelengths of light. - The brain processes the information received from cones to create the perception of color. - This process involves the interpretation of the wavelengths of light to determine the object's color. Limited Color Visions - correct answers - Dichromacy means having only two types of color receptors (cones) in the eyes. - Anomalous trichromacy also involves three types of cones but with sensitivity alterations. - Both conditions impact color perception. - Often linked to genetic variations located on the X-chromosome. Color Signifying Chemical Change - REDOX: - correct answers - REDOX reactions entail the transfer of electrons between substances. - These color transformations indicate the presence of REDOX (reduction-oxidation) reactions. - Examples include the oxidation of metals and the reduction of dyes, both leading to observable color transformations. Methylene Blue and the Blue Bottle Reaction - correct answers - Involves the oxidation of methylene blue. - Process leads to a change in the solution's appearance from transparent to blue. - The reaction effectively demonstrates the concept of oxidation in a visually striking manner. Color and Molecular Structure - correct answers - Molecular structure changes can impact the spacing of energy levels in molecules. - These alterations influence which wavelengths of light are absorbed and which are reflected. - The result is a change in the substance's color as it interacts with light. Indicators in Chemistry - correct answers - Indicators exhibit color changes in varying environments. - These changes occur due to alterations in the molecular structure of indicators. - The triggers for these color changes can be shifts in acidity or oxidation levels. - The indicator's molecular response to environmental changes results in observable shifts in color. Indicators in Chemestry - Second part - correct answers - Acids: contain large numbers of H+ ions - Bases: contain large numbers of OH- ions - Phenolphthelin: transparent in acids, magenta in bases. - Anothocyanin: Reds in acids, red-violet, purple in neutrals, yellow and green in bases Important for history of chemistry - correct answers - Perkin's violet: First synthetic dye manufactured. Accidental finding. - Alizarin crimson: First naturally found molecule that was synthetically copied. - Azo family: Scientists picked a colour - and were able to create it synthetically Adaptive Processes in Vision - correct answers - Color constancy and the Purkinje effect are processes involving the adaptation of the eye and brain. - They enable the maintenance of consistent color perception across varying light conditions. - Color constancy helps the brain adjust for changes in lighting to perceive objects with their true colors. - The Purkinje effect involves a shift in sensitivity toward shorter wavelengths in low-light conditions, impacting perceived colors.