Question

Give reason: Red color is selected for danger signals.

Answer 1

Scattering:

1. Light can be examined entirely from its source.
2. When light passes from one medium to another, say air, or a glass of water, then a part of the light is absorbed by particles of the medium, preceded by its subsequent radiation in a particular direction. This phenomenon is termed a scattering of light.
3. Due to this phenomenon, some light rays get absorbed while a few get scattered in various directions.
4. In this phenomenon, light rays deviate from their straight path when met with an obstacle like dust, water vapor, etc.
5. The deviated light beam is redirected in different directions.
6. The more the wavelength of color, the least it gets scattered.
7. According to Rayleigh's scattering, the amount of light scattered is inversely proportional to the fourth power of its wavelength. Mathematically, it is expressed as $I\propto \frac{1}{{\lambda }^4}$, where $I$ is intensity of light and $\lambda$ is the wavelength.

The red color is selected for danger signals:

1. The red color has the highest wavelength in the electromagnetic spectrum of red light.
2. Thus, the red color scatters the least. Also, the red color can travel through a long distance without being scattered.
3. Therefore, red color is used in danger signals so that a person heading towards it can clearly recognize the danger signal even from a distance.

Hence, the red color is selected for danger signals because it scatters the least.