The Arduino microcontroller is currently one of the favorite tools of makers, and many teachers have used it in teaching or experiments. In addition, light-emitting diode (LED) smart lighting is the worldwide trend in lighting. There are many teaching demonstrations or applications of color addition using LEDs. Furthermore, the Internet of Things…

Proteins are involved in nearly every biological process, which makes them of interest to a range of scientists. Previous work has shown that hand-held cameras can be used to determine the concentration of colored analytes in solution, and this paper extends the approach to reactions involving a color change in order to quantify protein…

A demonstration of the degradation of food coloring dyes by oxidation via the Fenton reaction can be substituted with a simpler demonstration using the oxidant oxone with iron(II) ions as an activator. The addition of small amounts of solid oxone and iron(II) sulfate to solutions containing mixtures of food coloring results in successive…

A simple and ecofriendly procedure was developed in order to prepare extracts from red and green leaves. This procedure enables the separation of yellow, green, and red band pigments and optimizes the previously reported baking soda "supermarket column". The same extract also led to a novel and colorful potato starch column, which can…

When dissolving copper in nitric acid, copper(II) ions produce a blue-colored solution. It is possible to determine the concentration of copper(II) ions, focusing on the hue of the color, using a smartphone camera. A free app can be used to measure the hue of the solution, and with the help of standard copper(II) solutions, one can graph a…

Teaching prismatic colours usually boils down to establishing the take-home message that white light consists of "differently refrangible" coloured rays. This approach explains the classical spectrum of seven colours but has its limitations, e.g. in discussing spectra from setups with higher resolution or in understanding the well…

A sticky capture thread from the spiral element of spider orb-webs is formed of almost regularly spaced droplets that surround a supporting axial fibre. From the perspective of physical optics it represents a periodic linear array of scattering elements that acts as a diffraction grating. This is a novel aspect, which is of vital importance for…

The colour of the copper layer deposited on a graphite electrode during electrolysis of an aqueous solution of copper(II) sulfate looks whitish-grey when inspected in situ. Taking the electrode out of the solution reveals the familiar orange-red colour of deposited copper. The explanation is found in terms of the almost ideal complementary colours…

Dyes aren't just for fabrics--colorants have been added to food for centuries to enhance its appearance. This monograph and teaching guide investigates both the compounds that give foods their natural color and synthetic colorants currently approved for use in foods. Problem-solving inquiry based activities involve high school level students in…

From prehistoric times people have been fascinated with color; from cave paintings to the latest computers, color has been a constant companion. Textiles are made more beautiful by the alteration or application of colorants. This teaching resource investigates vat dyes, a colorant class which includes the oldest dyes known as well as important…

From prehistoric times people have been fascinated with color; from cave paintings to the latest computers, color has been a constant companion. Textiles and craft items are made more beautiful by the alteration or application of colorants. This teaching resource investigates dyes obtained from natural sources, such as plants and animals. These…

A simple device used to demonstrate the main features of primary color addition is described. Materials needed to construct the device, procedures used, and typical results are discussed. (JN)

Describes an experiment enabling students to apply concept of diffraction, determine limits of their color perception, learn how to measure wavelength with a simple apparatus, observe continuous and line spectra, and associate colors with corresponding wavelengths. The homemade diffraction-grating spectrometer used is easily constructed. (JN)

Describes how color graphics are built up on microcomputer displays and how a range of colors can be produced. Discusses the logic of color formation, noting that adding/subtracting color can be conveniently demonstrated. Color generating techniques in physics (resistor color coding and continuous spectrum production) are given with program…

Describes an apparatus (called the "Rainbow Cup") used for demonstrating the colored rings produced by constructive interference in soap films. Discusses construction of the Rainbow Cup and gives hints for its use in the classroom, especially in relation to classroom humidity. (JM)