The red light from a helium-neon laser has a wavelength of 644.6 nm in air. Find the speed, wavelength, and frequency of helium-neon laser light in air, water, and glass. (The glass has an index of refraction equal to 1.50.)speed (m/s)wavelength (nm)frequency (Hz)airwaterglass

air  f = 4.6527 10¹⁴ Hz

water f = 3.4914 10¹⁴ Hz

glass f = 3.1027 10¹⁴ Hz

Explanation:

The refractive index of a material is given by

         n = c / v

where c is the speed of light in a vacuum c = 3 108 m / s and v is the speed of light in the material medium.

the speed of the wave is

         v = λ f

we substitute

         c / n = λ f

          f =

The refractive indices are

air 1,00029

water 1.3330

glass 1.5

let's calculate the frequencies

vaccum

         f = 3 10⁸ / 1 644.6 10⁻⁹

         f = 4.6540 10¹⁴ Hz

air

         f = 3 10⁸ / 1,00029 644.6 10⁻⁹

         f = 4.6527 10¹⁴ Hz

Water

         f = 3 10⁸ / 1.333 644.6 10⁻⁹

         f = 3.4914 10¹⁴ Hz

glass

        f = 3 10 ^ 8 / 1.5 644.6 10⁻⁹

        f = 3.1027 10¹⁴ Hz

c because the news are a source of information of things that happen on the daily and shows evidence about that particular topic

scattering of light by tiny particles in air to produce the colors we see on sky, is dependent on the following factors:

(i) wavelength of light

(ii) size of the scattering particle  

(iii) distance traveled by light through the atmosphere.

according to rayleigh's law of scattering, the amount of scattering is inversely proportional to the fourth power of its wavelength. shorter the wavelength, greater is its scattering. hence violet/blue light is scattered more than red.

sun's light is a composite light ( visible light) with wavelengths in the range 400 nm (violet) to 700 nm (red). as sunlight passes through our atmosphere, the molecules of air scatter light according to their wavelengths. during sunrise and sunset, the sun's position is below the horizon. hence light from the sun travels a greater distance in the atmosphere when compared to its position a noon.

as sunlight enters the earth's atmosphere, blue light is scattered away and at the end of its journey in the sky, only red and orange wavelengths remain in the beam.

hence at sunrise and sunset, the sky appears reddish orange.