Color Theory and Symbolism

Yes, it is correct. They respond to red, green and blue lights. The sensations of different colours are produced by various combinations of these cones and their photopigments. When these cones are stimulated equally, a sensation of white light is produced.

Yes, a letter box is red in colour.

If in any direction the bear is facing south, then the bear should be at the north pole. In northern polar region, only polar bears exist, which are white in colour.

Whenever an opaque object is kept in the path of the light, it forms a dark patch behind itself. This dark patch is known as a shadow. It is always black in colour irrespective of the object colour or light colour falling on it.

The visible spectrum of sunlight contains seven colors traditionally remembered by ROYGBIV - Red, Orange, Yellow, Green, Blue, Indigo, and Violet. These represent the range of wavelengths visible to the human eye, from longest (red) to shortest (violet).

When any solid material is heated to incandescence (glowing due to heat), it emits light according to blackbody radiation principles. The color depends on temperature - as temperature increases, the glow progresses from dull red to bright red, orange, yellow, white, and finally blue-white. A blue glass will still glow red first when heated because lower temperatures (around 700-800°C) produce red glow. The glass color only affects which wavelengths are transmitted in transmitted light, not the thermal emission color.

When all colors of the visible spectrum are combined in equal proportions, they produce white light. This principle was demonstrated by Isaac Newton using a prism - he showed that white light can be separated into colors and then recombined back into white light. This is why white light contains all colors.

To an astronaut in space, the sky appears black rather than blue. This is because there's no atmosphere to scatter sunlight and create the blue sky effect we see on Earth.

The letters of the word COLOR are all from the word CONTROL. So, COLOR = ZLILO.  

Pink is not a primary colour.

A red cross on a white background, when seen through a red filter, will become invisible.

In ILS marker beacon indicator lights, the Middle Marker is represented by amber (yellow-orange) color. The Outer Marker indicator is blue, and the Inner Marker indicator is white (if installed). These visual cues in the cockpit help pilots identify which marker they are crossing during approach.

In the additive color model (used for light and displays), the primary colors are red, green, and blue (RGB). Yellow is a secondary color formed by mixing red and green light. In subtractive color mixing (paints and pigments), yellow is considered a primary color along with magenta and cyan (or traditionally red, yellow, and blue). The question is referring to the additive color model.

Objects appear a certain color because they reflect that color's light wavelengths and absorb others. A blue object reflects blue light and absorbs red and green wavelengths. In red light (which lacks blue wavelengths), no blue light is available to reflect, so the object appears black.