Question

calculate the frequency of visible light at 3000amstrong travelling in vacuum​

Answer 1

Explanation:

Light has wave characteristics in various media as well as in a vacuum. When light goes from a vacuum to some medium, like water, its speed and wavelength change, but its frequency f remains the same. (We can think of light as a forced oscillation that must have the frequency of the original source.) The speed of light in a medium is

v

=

c

n

, where n is its index of refraction. If we divide both sides of equation c = fλ by n, we get

c

n

=

v

=

f

λ

n

. This implies that v = fλn, where λn is the wavelength in a medium and that

λ

n

=

λ

n

, where λ is the wavelength in vacuum and n is the medium’s index of refraction. Therefore, the wavelength of light is smaller in any medium than it is in vacuum. In water, for example, which has n = 1.333, the range of visible wavelengths is

380

nm

1.333

to

760

nm

1.333

, or λn = 285 to 570 nm. Although wavelengths change while traveling from one medium to another, colors do not, since colors are associated with frequency.