Sunlight is composed of seven colors of red, orange, yellow, green, cyan, blue, and purple, and their wavelengths and deflection angles are different. Sunlight irradiates objects, and various objects have different absorption and reflection abilities of light of different wavelengths, forming various colors. In short, if an object can reflect one or more kinds of light in the sunlight and absorb the rest, then the object will show the color of the reflected monochromatic or multi-color light. In visible light, the red light has the longest light wave and the smallest deflection angle, and easily passes through water layers, raindrops, dust and fog. The orange and yellow light is not afraid of obstruction, and can penetrate these objects. Therefore, the fire truck is painted red in order to make people see it all the way in foggy weather, dusty environment or stormy weather, and make way for it so that it can complete the fire fighting and rescue task as soon as possible.
