31 . 2 S I U N I T S O F L E N G T H M A S S A N D T I M E, ,There are ways of describing the physical world that do not involve measure-ment. For instance, we might talk about the color of a flower or a dress. But theperception of color is subjective; it may vary from one person to another. Indeed,many people are color-blind and cannot tell certain colors apart. Light received byour eyes can be described in terms of wavelengths and frequencies. Differentwavelengths are associated with different colors because of the physiologicalresponse of our eyes to light. But unlike the sensations or perceptions of color,wavelengths can be measured. They are the same for everyone. In other words,measurements are objective. Physics attempts to describe and understand nature in anobjective way through measurement.S T A N D A R D U N I T SMeasurements are expressed in terms of unit values, or units. As you are probablyaware, a large variety of units are used to express measured values.Some of the earliest units of measurement, such as th

the dimension of color that is determine by the wavelength of light; what we know as the color names blue, green, and so forth.

Which of the following describes the relationship between the wavelength of light and itsperceived color according to the information provided?A) Longer wavelengths are perceived as blue.B) Medium wavelengths are perceived as green.C) Shorter wavelengths correspond to the color red.D) All wavelengths are perceived as white light.

The sentences given in this question, when properly sequenced, form a coherent paragraph. Decide on the proper order for the sentences and write this sequence as your answer.1. There are many more spectra than colour sensations; in fact, one may formally define a colour to be the class of all those spectra which give rise to the same colour sensation.2. The light’s spectrum records each wavelength’s intensity.3. Electromagnetic radiation is a mixture of radiation of different wavelengths and intensities.4. The full spectrum of the incoming radiation from an object determines the visual appearance of that object, including its perceived colour.5. When this radiation has a wavelength inside the human visibility range, that radiation is called light.

The portion of colored light within the electromagnetic spectrum that is visible to the human eye.Group of answer choicesWavelengthVisible SpectrunFull spectrum lightNone of the above

What is false about color perception?a) Reflecting wavelength determines the color of an object.b) Chromatic colors reflect some wavelengths while not reflecting others.c) Achromatic colors don’t have wavelength selectivity. The wavelengths are reflected equally.d) White does not reflect any light.e) Black absorbs most wavelengths of visible light