Class 10

Electromagnetic Spectrum : The Trick to Memorize the Order of Wavelengths and Frequencies


Introduction to Electromagnetic Waves or EM waves

Electromagnetic radiation (EM waves) is one of the many ways by which energy travels through space. The heat from a burning fire, the light from the sun, the X-rays used by your doctor, as well as the energy used to cook food in a microwave are all forms of electromagnetic radiation. While these forms of energy might seem quite different from one another, they are related in that they all exhibit wavelike properties.

EM waves is classified into types according to the frequency of the wave. These types include, in order of increasing frequency, radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays and gamma rays.

EM Spectrum with examples

As we can see, the visible spectrum—that is, light that we can see with our eyes—makes up only a small fraction of the different types of radiation that exist.

To the right of the visible spectrum, we find the types of energy that are lower in frequency (and thus longer in wavelength) than visible light.

These types of energy include infrared (IR) rays (heat waves given off by thermal bodies), microwaves, and radio waves. These radiation surround us constantly, and are not harmful, because their frequencies are very low.

To the left of the visible spectrum, we have ultraviolet (UV) rays, X-rays, and gamma rays.

These types of radiation are harmful to living organisms, due to their extremely high frequencies (and thus, high energies). It is for this reason that we wear suntan lotion at the beach (to block the UV rays from the sun)

This is also the reason why an X-ray technician will place a lead shield over us, in order to prevent the X-rays from penetrating anything other than the area of our body being imaged.

Gamma rays, being the highest in frequency and energy, are the most damaging. Luckily though, our atmosphere absorbs gamma rays from outer space, thereby protecting us from harm.

NOTE : Excerpt has been taken from the following link
https://www.khanacademy.org/science/physics/light-waves/introduction-to-light-waves/a/light-and-the-electromagnetic-spectrum

Short Trick to Memorize EM Spectrum

To memorize and recall the wavelength and frequency order of the EM spectrum we will memorize the code :

Ra M I L U X Y

This is the decreasing order of wavelength and
increasing order of frequency

Here,
Ra = Radio waves
M = Micro waves
I = Infrared waves
L = Light waves (Visible Light)
U = Ultraviolet rays
X = X rays
Y = Gamma rays ( as Y resembles Gamma)

One point to note in this code is that in Light waves or L, VIBGYOR should be written from Right to Left as –

Ra M I L ( R O Y G B I V ) U X Y

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Published on October 24th, 2019 | by Abhishek Mandal


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