Why is the sky blue? The earth is surrounded by an atmosphere.

The blue component of the spectrum of visible light has shorter wavelengths and higher frequencies than the red component. Thus, as sunlight of all colors passes through air, the blue part causes charged particles to oscillate faster than does the red part. The faster the oscillation, the more scattered light is produced, so blue is scattered more strongly than red. For particles such as air molecules that are much smaller than the wavelengths of visible light the difference is dramatic. The acceleration of the charged particles is proportional to the square of the frequency, and the intensity of scattered light is proportional to the square of this acceleration. Scattered light intensity is therefore proportional to the fourth power of frequency. The result is that blue light is scattered into other directions almost 10 times as efficiently as red light.

current flows in a wire

myth. it was once thought that animals, including cats and dogs, could only see in black and white. however, scientists have proven this to be a myth. in all animals, including humans, the perception of colour is determined by the presence of cells in the eye called cone photoreceptors.