Name: electromagnetic waves: uses across the spectrum
Uploaded: 2020-09-03T13:38:27.000Z
Duration: 2 min 37 s
Channel: JoVE

K12 Standards

Pennsylvania State Academic Standards

9-12

Earth and Space Science

Earth's Systems

3.3.9-12.H

The Electromagnetic Spectrum

電磁スペクトルとは 電磁波の周波数と それに対応する 波長の範囲のことです 波長と周波数は 互いに反比例しており 波長が長いほど 周波数は低くなります 電磁波のエネルギーは プランクの式で 示されるように その周波数に 正比例します したがって 最もエネルギーの 高い電磁波は 最も波長が 短いということになります 電磁波は その周波数や波長によって 電波 マイクロ波 赤外線 X線 可視光線 紫外線 ガンマ線 などに分類されます 通信システム間で信号を 伝達するために使用される電波は 波長が最も長く 周波数が最も低く エネルギー量が最小です 次に波長が長いのが マイクロ波です その用途は レーダーシステムから家庭で 食品を加熱するための 電磁波の範囲です 次に赤外線ですが これは暖かい物体から放射される 熱放射の 大部分を占めています 例えば 地球は 太陽から放射される 放射エネルギーの一部として 赤外線を吸収し それ自体が赤外線を 宇宙空間に放出しています 可視光の波長はさらに短く 740～390ナノメートルです 赤色光は 最も長い波長を持ち 紫色は最も短い 波長を持っています 人間の目は この狭い波長域にしか 反応しません 紫外線はさらに 短い波長を持っています 紫外線の中で 最も身近なのは太陽光で 過剰に浴びると火傷をしたり 皮膚がんになったりするほどの エネルギーを持っています X線やガンマ線は 最も波長が短く 電磁波の中でも最も エネルギーの高い放射線です X線は多くの物質を 通過することができますが 骨を通過することは 容易ではありません そのため 重要な イメージングツールです ガンマ線は 特定の放射性元素の 崩壊連鎖中に放出されることで 最もよく知られています ガンマ線とX線の間には 普遍的な区別はありませんが ガンマ線は一般的に 最短波長で最高周波数となり 最高エネルギーを 持つと考えられています

電磁スペクトル

電磁スペクトルは、あらゆる種類の電磁波を周波数と波長に応じて並べたものです。 可視光のさまざまな色にはそれぞれ固有の周波数と波長があり、可視光は電磁スペクトルのごく一部を構成していることがわかります。 電磁スペクトルのさまざまな部分で機能するように開発された技術は、利便性や歴史上の問題があるため、通常、スペクトルのさまざまな部分に異なる単位が使用されています。 たとえば、通常、電波は周波数（通常は MHz 単位）として指定され、可視領域は通常、波長（通常は nm またはオングストローム単位）で指定されます。  
 
 <img alt="Eq1" src="https://www.jovecore.com/CDNSource/lessons/975/975Image_1.png" style="width: 700px;" /> 
 図 1 ：電磁スペクトルは、周波数の高い順、波長の低い順に並んでいます。 
 
 電磁波の種類には、電波、電子レンジ、紫外線、可視光線、赤外線、 X 線とガンマ線があります。 
 
 電波は、最も長い波長、最も低い周波数を持ち、エネルギー量が最も少なくなります。 携帯電話技術、ラジオ、テレビ放送、航空交通管制などに使用されています。 
 
 マイクロ波は電波よりも波長が短いです。 それらは水によって吸収され、食べ物を熱し、調理するのに使用されます。  
 
 次に赤外線があり、これは暖かい物体から放射されています。 例えば、地球は太陽から放射エネルギーを吸収し、赤外線を放射しています。 一部の赤外線は大気中に吸収・再放射され、温室効果を利用して地球の平均気温を維持しています。 暗視ゴーグルは、私たちの体から放出される赤外線を感知します。 
 
 可視光は、 740 ～ 390 nm の電磁放射のごく一部に過ぎません。  人間の目は、このような狭い範囲の波長しか見ることができません。 可視光は主に、赤、橙、黄、緑、青、藍、紫の7つの色成分で構成されています。  
 
 紫外線には 400 ～ 10 nm の波長があります。 太陽光は、最もよく知られている紫外線源です。 それは、過度に浴びると日焼けを引き起こす十分なエネルギーを持ちます。 
 
 X 線は多くの物質を通過し、重要な画像処理ツールとなっています。 歯科医は診断目的で X 線を使用し、空港のセキュリティは X 線を使用してスーツケース内の荷物を視覚化します。 
 
 ガンマ線は、より短い波長に、高周波数、高エネルギーを持ちます。 ガンマ線は、核反応と自然発生する放射性元素によって放出されます。 
 
 X 線とガンマ線は最もエネルギーの高い電磁波です。 高エネルギーは原子や分子をイオン化することができます。 電離放射線は生体分子に恒久的な変化や損傷を与える可能性があります。 がん細胞を破壊するために使用されます。   
 
 本書は <a href="https://openstax.org/books/chemistry-2e/pages/6-1-electromagnetic-energy">、 Openstax 、 Chemistry 2e 、 Section 6.1 ： Electromagnetic Energy から引用しています。</a>

電磁スペクトルは、周波数と波長に従って配置されたすべてのタイプの電磁放射で構成されています。それぞれ...

Education

JoVE Core

Chemistry

化学

Electronic Structure of Atoms

原子の電子構造

KEY TERMS AND CONCEPTS

主要用語と概念

electromagnetic waves: uses across the spectrum

The electromagnetic spectrum includes all electromagnetic radiation arranged by frequency and wavelength. Visible light is only a small part of it, and each color of visible light has its own frequency and wavelength. Different parts of the spectrum also use different units. Radio waves are usually measured in MHz, while the visible range is often measured in nm or angstroms.

The spectrum is organized from radio waves to gamma rays as frequency increases and wavelength decreases. Radio waves have the longest wavelengths, the lowest frequencies, and the least energy. They are used in cell phones, radio and television broadcasts, and air-traffic control. Microwaves have shorter wavelengths than radio waves and are absorbed by water, which is why they can heat and cook food.

Infrared radiation is next and is emitted by warm objects. The Earth absorbs energy from the Sun and gives off infrared radiation. Some of this radiation is absorbed and re-emitted by the atmosphere, which helps keep Earth’s average temperature stable through the greenhouse effect. Night vision goggles also detect the infrared radiation that our bodies emit.

Visible light spans only about 740 to 390 nm, so the human eye can see just a narrow band of electromagnetic radiation. This band includes red, orange, yellow, green, blue, indigo, and violet. Ultraviolet radiation has wavelengths from about 400 to 10 nm. Sunlight is the most familiar source of UV radiation, and too much exposure can cause sunburn.

X-rays can pass through many materials, so they are useful for imaging. Dentists use x-rays for diagnosis, and airport security uses them to view what is inside a suitcase. Gamma rays have even smaller wavelengths, higher frequencies, and higher energies. They come from nuclear reactions and naturally occurring radioactive elements. X-rays and gamma rays are the most energetic forms of electromagnetic radiation, and their ionizing radiation can damage biological molecules. Because of that, they can be used to destroy cancer cells.

Electromagnetic Waves: Uses Across the Spectrum

electromagnetic-waves-uses-across-the-spectrum

the wave nature of light

Measuring Light with Wavelength and Frequency

Light can be described as an electromagnetic wave, and its behavior helps explain many patterns seen in science. For centuries, scientists have tried to understand light. Newton used lenses and prisms to show that white light is made of the colors of the rainbow mixed together. He explained light as tiny particles moving at high speed. Other scientists, including Christiaan Huygens, showed that reflection and refraction could also be explained by treating light as a wave. At the time, people...

the electromagnetic spectrum

The electromagnetic spectrum includes all electromagnetic radiation arranged by frequency and wavelength. Visible light is only a small part of it, and each color of visible light has its own frequency and wavelength. Different parts of the spectrum also use different units. Radio waves are usually measured in MHz, while the visible range is often measured in nm or angstroms. The spectrum is organized from radio waves to gamma rays as frequency increases and wavelength decreases. Radio waves...

interference and diffraction

Wave Patterns from Light and Slits

Light can form wave patterns through interference and diffraction. When two electromagnetic waves meet with their peaks and troughs lined up, they combine into a larger wave. This is constructive interference, and the waves are in phase. When a peak of one wave meets a trough of the other, the waves reduce each other. This is destructive interference, and the result has a much lower amplitude. Diffraction is another wave behavior. When light passes through a slit that is about the same size as...

photoelectric effect

Why Light Ejects Electrons from Metals

Light can eject electrons from a metal surface when it has the right frequency. This process is called the photoelectric effect. Each metal has its own threshold frequency, which is the minimum light frequency needed to free electrons. Light below the threshold frequency cannot cause emission, even if it is very bright. When the light frequency is above the threshold, electrons are ejected. In that case, the number of electrons released is directly proportional to the intensity, or brightness,...

the bohr model

Bohr’s Quantized Atomic Orbits

Bohr’s quantized atomic orbits explain why hydrogen atoms can stay stable. Early in the twentieth century, Ernest Rutherford and his colleagues described atoms as tiny dense nuclei with lighter electrons moving around them. This picture was called the planetary model because it compared the atom to a miniature solar system, with electrons orbiting the nucleus like planets around the sun. The simplest atom is hydrogen. It has one proton in the nucleus and one electron moving around it. In the...

emission spectra

Line Spectra from Heated Gases

Line spectra are produced when heated gases give off light at specific wavelengths. In contrast, hot solids, liquids, or condensed gases radiate excess energy as a continuous spectrum. That spectrum contains an unbroken range of wavelengths. A gas at low partial pressure can produce a line spectrum when it is excited by an electric current or heated. Fluorescent light bulbs and neon signs work in this way. Each element has its own characteristic set of lines, and molecules can also produce...

the de broglie wavelength

Electron Waves and Standing Orbits

Electron waves and standing orbits explain how tiny particles can behave like waves. Large objects in the macroscopic world, like a billiard ball on a table, follow classical physics. A ball keeps moving in a straight line unless it hits another ball or a force such as friction acts on it. It also has a well-defined position, velocity, and momentum, where momentum is mass times velocity. Waves behave differently from macroscopic particles. When waves interact, they can form interference...

the uncertainty principle

Electron Position and Momentum Limits

Heisenberg’s uncertainty principle sets a limit on how precisely we can know an electron’s position and momentum at the same time. Momentum is the motion of a particle, and the two measurements affect each other. If the momentum is known more accurately, the position becomes less certain, and the reverse is also true. Heisenberg described this limit with an equation that uses Planck’s constant. The equation shows the smallest possible uncertainty for position and momentum together. It explains...

the quantum-mechanical model of an atom

Electron Orbitals in Quantum Mechanics

Quantum mechanics explains how electrons behave in atoms using waves and probability. Erwin Schrödinger built on de Broglie’s idea that an electron in hydrogen could act like a circular standing wave instead of moving in fixed circular paths. He then derived the Schrödinger equation, which became a major step in modern atomic theory. When Schrödinger applied his equation to hydrogen-like atoms, it matched Bohr’s energy expression and the Rydberg formula for hydrogen spectra. He described...

quantum numbers

Electron Orbitals and Spin

Electron orbitals are described by quantum numbers that show where an electron is most likely to be found around the nucleus. These numbers come from the quantum mechanical model, which is based on solutions of the Schrödinger equation. They also help explain why electron energy comes in set values instead of changing smoothly. The principal quantum number, n, labels the energy level. It can be 1, 2, 3, and so on, and higher n values usually mean higher electron energy. This number also tells...

atomic orbitals

Electron Regions in Atomic Orbitals

Electron regions in atomic orbitals show where an electron is most likely to be found in an atom. These three-dimensional regions are often drawn as boundary surfaces around the densest part of the cloud. The shape of an orbital depends on the angular momentum quantum number, l. This value can range from 0 to n - 1, where n is the principal quantum number. For n = 1, only l = 0 is allowed. For n = 2, both l = 0 and l = 1 are allowed. Orbitals with the same value of l form a subshell. The l =...

the pauli exclusion principle

Electron Spin and Orbital Pairing

Electron spin and orbital pairing explain why only two electrons can fit in one atomic orbital. Electron configuration describes how electrons are arranged in an atom’s orbitals. It is written with three parts: the principal quantum number, n, the orbital type, or subshell, and a superscript that shows how many electrons are in that subshell. For example, 2p4 means four electrons in a p subshell with n = 2, and 3d8 means eight electrons in a d subshell with n = 3. The three quantum numbers...

the energies of atomic orbitals

Shielding and Orbital Penetration

Shielding and orbital penetration help explain why electrons in an atom have different energies. Electrons are attracted to the positive nucleus, but they also repel one another in atoms with more than one electron. The strength of these forces depends on the charge and the distance between the particles. Opposite charges attract, like charges repel, and the force gets weaker as the particles move farther apart. An electron that stays closer to the nucleus is held more tightly. That means...

the aufbau principle and hund's rule

Electron Filling Order in Atomic Orbitals

Electron filling order in atomic orbitals follows the aufbau principle and Hund's rule. To write an electron configuration, we build atoms in order of atomic number. Starting with hydrogen and moving across the periods of the periodic table, one proton is added to the nucleus and one electron is placed into the correct subshell. This process describes the ground-state electron configurations of the elements. The aufbau principle comes from the German word aufbau, which means "to build up." It...

electron configuration of multielectron atoms

electron-configuration-of-multielectron-atoms

Valence Electrons and Noble Gas Shorthand

Valence electrons and noble gas shorthand help show how electrons are arranged in multielectron atoms. Sodium, the alkali metal with atomic number 11, has one more electron than neon. That extra electron goes into the lowest-energy subshell available, the 3s orbital, so sodium has the configuration 1s2 2s2 2p6 3s1. Electrons in the outermost shell, where n is highest, are called valence electrons. Electrons in the inner shells are called core electrons. Because core electrons often match a...

key terms and concepts

Explore the electromagnetic spectrum from radio waves to gamma rays, including visible light, infrared, UV, X-rays, and their real-world uses.

Electromagnetic Waves: Uses Across the Spectrum | JoVE K12

chemistry

JoVE Core 化学は、簡潔で理解しやすいアニメーションビデオレッスンを使用して、一般的な化学の概念を生き生きとしたものにします。さらに、活動する科学者のビデオでは、現在世界中の実験室で行われている古典的そして独創的な研究・実験をお見せします。

Weather and Climate

3.3.9-12.E

Physical Science

Waves and Electromagnetic Radiation

3.2.9-12.X

Louisiana Student Standards for Science

High School

Earth Science

Earth’s Systems

HS-ESS2-4

Tennessee Academic Standards

Physics

waves-and-their-applications-in-technologies-for-information-transfer

Waves and Their Applications in Technologies for Information Transfer

PHYS.PS4.7

PHYS.PS4.8

Arizona Science Standards

HS+C.P1

HS+C.P1U1.2

new-jersey-student-learning-standards-for-science

New Jersey Student Learning Standards for Science

HS-PS4-4

Alabama Course of Study Science

Matter and Its Interactions

9-12.C.1.1.c

Earth's Place in the Universe

9-12.ESS.1.2

9-12.ESS.1.2.a

Next Generation Science Standards

Florida Department of Education

SC.912.E.5

SC.912.E.5.8

SC.912.P.8

SC.912.P.8.3

SC.912.P.10

SC.912.P.10.19

south-carolina-college-and-career-ready-science-standards

South Carolina College and Career Ready Science Standards

C-PS4-4

C-PS4-5

P-PS4-4

new-york-state-science-learning-standards

New York State Science Learning Standards

HS. Chemical Reactions

HS-PS1-7.

HS. Waves and Electromagnetic Radiation

HS-PS4-3.

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3.3.9-12.I

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3.3.9-12.K

Electromagnetic Waves: Uses Across the Spectrum

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