Electromagnetic Spectrum Definition for Kids

Electromagnetic Spectrum Definition for Kids


Electromagnetic spectrum is the entire range of radiation that the sun produces and emits, a part of which is received by our planet earth. In some discussions, electromagnetic spectrum is often referred to as the heat generated by the sun and that heat traveling across the space and reaching different planets and satellites in the solar system. At times electronic magnetic spectrum is used to refer to the light emitted by the sun. It is not the heat or light in isolation. Electromagnetic spectrum pertains to the entire range of electromagnetic radiation of the sun, which includes heat and light.

Electromagnetic Spectrum: Explained

The sun has a substantial range of electromagnetic radiation. It is felt as heat and observed as light when it hits opaque objects in space but there is a large part of the radiation that is neither felt as hot nor observed as light in plain vision; that is unaided human sight. These radiations travel in waves. It is similar to how waves are created in the sea, lakes or even a small pond. Just as you would create waves if you throw a pebble or stone in a pond, lake or river, the sun creates waves of electromagnetic radiation. Some waves are very small, like the ones created in a lake if you throw a small stone. Some waves are large, like the ones created in a lake if you drop a large boulder in the water. You can consider the smaller waves as ripples in the river and the larger electromagnetic waves as the large waves in the sea. Just as the waves in rivers, lakes and seas vary, depending on the tides and other factors, the electromagnetic waves also vary in their sizes and distance traveled. Waves are measured as wavelengths.

Electromagnetic spectrum is the complete range that includes all the wavelengths of electromagnetic radiation. From the tiniest of wavelengths to the largest wavelength, everything forms the complete electromagnetic spectrum.

Types of Waves in the Electromagnetic Spectrum

For convenience and ease of study, the entire range of wavelengths has been broken down into three categories: short waves, medium sized waves and long waves. The short waves are known as ultraviolet waves. The midsized waves are known as visible light or visible light waves. The longer waves are known as infrared waves. The longest waves are further classified as radio waves and micro waves among others.

Let us quickly check the various types of electromagnetic waves and their wavelengths. To keep it simple, we are avoiding the frequency and energy of such waves.

  • The shortest wave is gamma rays with a wavelength of less than 10 pm. Then comes x-rays with wavelengths shorter than 10 nm. Extreme ultraviolet or UV has wavelength shorter than 200 nm and near UV has wavelength shorter than 380 nm.
  • Visible light shares a small range of wavelength with near UV and can be up to 780 nm. Wavelengths greater than that of visible light are infrared (IR).
  • Near IR has wavelength shorter than 2.5 um, mid IR is shorter than 50 um, far IR is shorter than 1 mm, microwaves are shorter than 100 mm and then there are radio waves. Radio waves are classified as ultrahigh frequency radio with wavelength shorter than 1 m, very high frequency radio is shorter than 10 m, shortwave is less than 180 m, medium radio wave is short of 650 m and long wave is short of 10 km. Very low frequency radio wave has a wavelength greater than 10 km.

Ultraviolet, visible light and infrared have been well defined and classified based on their wavelengths but every category does overlap with its preceding and succeeding category for a considerable portion of one another’s wavelengths. It has been observed that low energy gamma rays can have wavelengths greater than high energy x-rays.

These wavelengths are in vacuum or space. The wavelengths vary very little when the radiation enters the earth’s atmosphere. The air of our planet doesn’t interfere much with the wavelengths. However, if there is an opaque body or some kind of obstruction and medium that is not as unaffecting as the air or our atmosphere, then there can be substantial changes to the wavelengths of most waves.

The entire range of waves, right from gamma rays to very low frequency radio waves is the electromagnetic spectrum. This is the reason why it is factually and technically incorrect to simply refer to the visible light or the heat generated by the sun as the basis of the electromagnetic spectrum. It is essentially all the waves and not just what we can see or feel.

The recently discovered gravitational waves, which have been observed not once but twice now and the inferences have been peer reviewed, are not a part of the electronic spectrum.