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Light is an electromagnetic wave that can be perceived by the human eye. It is approximately in the middle of the electromagnetic spectrum. It is preceded by microwaves, radio waves and infrared rays. After visible light we find ultraviolet radiation, X-rays and gamma rays in increasing order of frequency.
With the help of a spectroscope we can observe the electromagnetic spectrum and we can also make measurements of wavelength or frequency of radiation.
visible light
Visible light is part of a narrow band of the electromagnetic spectrum that goes from the wavelength of 380 nm to 780 nm. The colors of the spectrum are arranged just like a rainbow.
Wavelength
The length of the light wave refers to the distance between subsequent crests or troughs in the wave.
wave frequency
Frequency is the number of waves that pass a given point in one second.
In the expression c = λν , where c is the speed of light in a vacuum, ν is the frequency, and λ is the
wavelength.
Taking into account the previous formula:
wavelength = speed of light / frequency
frequency = speed of light / wavelength
The Northern Lights
The Aurora Borealis represents a perfect example to pose the wavelength calculation problem. This nocturnal spectacle occurs due to radiation interacting with the earth’s magnetic field. Its characteristic green color has a frequency of 5.38 x 10 14 Hz. What is the wavelength of this light?
We proceed as follows:
λ = c / nu
λ = 3 x 10 8 m / sec / (5.38 x 10 14 Hz)
λ = 5.576 x 10 -7 m
1 nm = 10 -9 m
λ = 557.6 nm
Thus, the wavelength of green light is 5.576 x 10 -7 m or 557.6 nm.
References
Inaoé (s/f). Chapter 1. What is light? Available at: https://www-optica.inaoep.mx/~jjbaezr/INAOECursos/colorimetria/pdefes/luz.pdf
Núñez, L. (2013). Basic notions of light. Available at: https://www.uv.mx/personal/lenunez/files/2013/06/luz.pdf
