Show Electromagnetic waves have an extremely wide range of wavelengths, frequencies, and energies. The highest energy form of electromagnetic waves are gamma (γ) rays and the lowest energy form are radio waves. The figure below shows the electromagnetic spectrum, which is all forms of electromagnetic radiation. On the far left of Figure \(\PageIndex{1}\) are the highest energy electromagnetic waves. These are called gamma rays and can be quite dangerous, in large numbers, to living systems. The next lower energy form of electromagnetic waves are called x-rays. Most of you are familiar with the penetration abilities of these waves. They can also be dangerous to living systems. Humans are advised to limit as much as possible the number of medical x-rays they have per year. Next lower, in energy, are ultraviolet rays. These rays are part of sunlight and the upper end of the ultraviolet range can cause sunburn and perhaps skin cancer. The tiny section next in the spectrum is the visible range of light. The visible light spectrum has been greatly expanded in the bottom half of the figure so that it can be discussed in more detail. The visible range of electromagnetic radiation are the frequencies to which the human eye responds. Lower in the spectrum are infrared rays and radio waves.  The light energies that are in the visible range are electromagnetic waves that cause the human eye to respond when those frequencies enter the eye. The eye sends a signal to the brain and the individual "sees" various colors. The highest energy waves in the visible region cause the brain to see violet and as the energy decreases, the colors change to blue, green, yellow, orange, and red. When the energy of the wave is above or below the visible range, the eye does not respond to them. When the eye receives several different frequencies at the same time, the colors are blended by the brain. If all frequencies of light strike the eye together, the brain sees white. If there are no visible frequencies striking the eye, the brain sees black. The objects that you see around you are light absorbers—that is, the chemicals on the surface of the object will absorb certain frequencies and not others. Your eyes detect the frequencies that strike your eye. Therefore, if your friend is wearing a red shirt, it means the dye in that shirt absorbs every frequency except red and the red frequencies are reflected. If your only light source was one exact frequency of blue light and you shined it on a shirt that was red in sunlight, the shirt would appear black because no light would be reflected. The light from fluorescent types of lights do not contain all the frequencies of sunlight and so clothes inside a store may appear to be a slightly different color when you get them home. Summary
What is High-Energy?The radiation that we call "light" is only a small section of the electromagnetic spectrum. The whole spectrum spans from very long wavelengths (= low frequencies = low energies) usually called the radio regime, to the very short wavelengths (= high frequencies = high energies) which are called Gamma-rays. High-Energy is called the radiation above (towards higher energies) the ultraviolet (UV), i.e. X-rays and Gamma-rays. What is X-ray Astronomy X-ray astronomy deals with phenomena which occur at the end of the stellar lifetimes: supernova explosions, neutron stars, and stellar black holes. Far outside our own Galaxy, the X-ray sky is dominated by active galaxies (radio galaxies, Seyfert galaxies, and quasars) with accreting supermassive black holes in their centers and by clusters of galaxies, the largest physical formations of our universe. Also, normal stars and galaxies can be studied with modern X-ray telescopes. And even comets and planets in the solar system are seen in X-rays. A short introduction to X-rays and X-ray Astronomy can be found in NASA's "Imagine the Universe" pages: (level 1: basic) and (level 2: scientific). What is Gamma-ray Astronomy? Gamma-rays are the most energetic form of electromagnetic radiation, with over 10,000 times more energy than visible light photons. If you could see Gamma-rays, the night sky would look strange and unfamiliar. The familiar sights of constantly shining stars and galaxies would be replaced by something ever-changing. Your Gamma-ray vision would peer into the hearts of solar flares, supernovae, neutron stars, black holes, and active galaxies. Gamma-ray astronomy presents unique opportunities to explore these exotic objects and the most energetic phenomena they produce. By exploring the universe at these high energies, scientists can search for new physics, testing theories and performing experiments which are not possible in earth-bound laboratories. The energy band of gamma-ray astronomy (or more precise Gamma-ray astrophysics) extends over more than seven orders of magnitude, from typically 500 keV to more than 1 TeV. It is thus not surprising that a wide variety of detectors are used to study smaller sub-ranges. Most gamma-rays are absorbed by the Earth's atmosphere. Thus, cosmic gamma-rays are typically observed from high-altitude balloons and satellites. A short introduction to gamma-rays and gamma-ray astronomy can be found in NASA's "Imagine the Universe" pages: (level 1: basic) and (level 2: scientific). Which electromagnetic wave has the lowest energy?Radio waves have photons with the lowest energies. Microwaves have a little more energy than radio waves. Infrared has still more, followed by visible, ultraviolet, X-rays and gamma rays.
How do you know which wave has the highest energy?(b) The wave with the shortest wavelength has the greatest number of wavelengths per unit time (i.e., the highest frequency). If two waves have the same frequency and speed, the one with the greater amplitude has the higher energy.
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Which electromagnetic wave has the highest energy
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