Name: measuring light with wavelength and frequency
Uploaded: 2020-09-03T13:38:27.000Z
Duration: 2 min 12 s
Channel: JoVE

K12 Standards

Texas Essential Knowledge and Skills

High School

Chemistry and Physics

IPC.7

IPC.7.E

The Wave Nature of Light

太陽光や 食品を加熱するために 使用されるマイクロ波 Wi-Fiルーターから 放射される電波は すべて電磁波の例です 電磁放射は 電荷を帯びた粒子の 運動から生じる エネルギーの伝達です この運動は 垂直に振動する 電場と磁場を作り 波の形で 空間を伝搬します 電磁波は 他の波と同様に 振幅 波長 周波数によって 特徴づけられます ピーク振幅は 波の中間線からピーク または谷までの距離です これは 波の強度を決定します 振幅が大きければ大きいほど 光は明るく あるいはより強くなります 波長は 連続したピークや 谷のような隣接する 波の同一点間の距離であり ギリシャ文字の ラムダによって表されています 電磁放射は キロメートルから ピコメートルまでの範囲で あらゆる長さの波長によって 分類することができます 例えば 可視光の 波長範囲は それぞれ 紫と赤の光に対応する 約400〜750ナノメートル です ギリシャ文字Ννで 象徴される周波数は １秒間に基準点を通過する 波の周期の数であり ヘルツ または１秒あたりの 周期で測定されます 波長は1サイクルの幅です 波の速度は 周波数と波長の 積です したがって 波の周波数は 波の進行速度に 正比例します しかし 周波数は波の波長に 反比例します そのため 電波のように 波長の長い波は 周波数が低くなります これらの波は ガンマ線のように 周波数が高く 波長の短い波に比べて エネルギーが低くなります

光の波の性質

光の性質は古代から探求されてきました。 17 世紀、アイザック・ニュートンはレンズとプリズムを使った実験を行い、白色光が虹の各色を組み合わせたものであることを実証しました。 ニュートンは、ニュートンの運動法則に従って、非常に小さな粒子の流れで構成された光の「粒子」像という観点から、この光学的所見を説明しました。  
 
 クリスチャン・ホイヘンスのような 17 世紀の他の人々は、反射や屈折などの光学現象が、すべての空間に浸透していると考えられていた「発光エーテル」という媒体を高速で通過する波として、光を説明できる可能性があることを示していました。 19 世紀初頭、トーマス・ヤングは、狭い間隔を通過した光が干渉縞を生じることを示し、ニュートンの粒子では説明できないが、波であれば容易に説明できることを示しました。 19 世紀後半、ジェームズ・クラーク・マクスウェルが電磁放射理論を開発し、光が広大な電磁波のスペクトル中の可視部分であることを示してから、光に対する粒子の見方は完全に否定されました。  
 
 19 世紀末までは、科学者たちは物理的な宇宙を大まかに 2 つの別々の領域から構成されるものと見ていました。ニュートンの運動法則に従って移動する粒子から構成された物質と、マクスウェルの方程式によって制御される波から構成された電磁波です。 現在では、これらの領域は古典力学と古典的な電気力学（または古典的な電磁気学）と呼ばれています。 この枠組みの中では説明できない物理的な現象がいくつかありましたが、当時の科学者たちは、この枠組みの全体的な健全性に非常に自信を持っていたため、これらの異常現象を「不可解なパラドックス」と捉え、この枠組みの中で最終的には何らかの形で解決される考えていました。 これらのパラドックスは、粒子と波動を基本的なレベルで密接に結びつける「粒子と波動の二重性」と呼ばれる現代の枠組みにつながり、古典的な見方に取って代わることになりました。 
 
 可視光をはじめとする電磁放射線は、原子や分子内の電子のエネルギーを推測することができるため、化学の分野で重要な役割を果たしています。 現代のテクノロジーの多くは、電磁放射線に基づいています。 たとえば、携帯電話の電波、歯科医が使用する X 線、電子レンジで食品を調理するために使用されるエネルギー、赤熱物体からの放射熱、テレビ画面からの光は、いずれも波動的な振る舞いをする電磁放射です。 
 
 <h4>波 </h4>
 
 波とは、空間内のある地点から別の地点にエネルギーを伝達できる振動または周期的な動きのことです。 波の一般的な例は、私たちの周りにたくさんあります。 ロープの端を振ると、自分の手からロープのもう一方の端にエネルギーが伝わり、池に小石を落とすと水の表面に沿って外に波紋が広がります。また、落雷に伴う空気の膨張により、数マイルにわたって音波（雷）が伝わります。 これらの場合、運動エネルギーは物質（ロープ、水、または空気）を通して伝達されますが、物質は基本的にその場に留まっています。  
 
 波は物質の中を伝わるだけではありません。 マクスウェルが示したように、電磁波は垂直な磁場で段階的に振動する電場で構成されており、どちらも進行方向に対して垂直です。 これらの波は、光の速度（cで示される）である 2.998 × 108 m/s の一定の速さで真空を通過できます。 
 
 電磁放射の形態を含むすべての波は、波長（ λ 、ギリシャ文字の小文字のラムダで示される）、周波数（ν、ギリシャ文字の小文字ニューで示される）、および振幅で特徴付けられます。  
 
 波長とは、連続する 2 つの山または谷の間の距離である（ SI 単位系ではメートル単位で測定）。 電磁波の波長は、キロメートル（103m）からピコメートル（10−12m）まで、非常に広い範囲で観測されています。 周波数とは、指定した時間（ SI 単位系では秒）内に特定の空間を通過する波の周期の数です。 1周期は完全な1波長に相当します。 周波数の単位はヘルツ（ Hz ）で、 1 秒あたりの周期の数（ s − 1 ）で表されます。 この単位の一般的な倍数はメガヘルツ（ 1 MHz = 1 × 106 Hz ）およびギガヘルツ（ 1 GHz = 1 × 109 Hz ）です。  
 
 振幅は波の変位の大きさに相当し、山と谷の間の高さの半分に相当します。 振幅は波の強さに関連しており、光の場合は輝度、音の場合は大きさを表します。 波の波長（ λ ）とその周波数（ ν ）の積 λ ν は波の速度です。 したがって、真空中の電磁放射の場合、速度は基本定数 cと等しくなります ： 
 
 <img alt="Eq1" src="https://www.jovecore.com/CDNSource/lessons/974/974_Equations-01.png" style="height: 40px;" />
 
 波長と周波数は反比例します。波長が大きくなると周波数が低下します。 電磁スペクトルとは、あらゆるタイプの電磁放射の範囲のことです。  
 
 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>

光の性質は、古くから研究の対象となってきました。17世紀に、アイザック・ニュートンはレンズとプリズムで実験を行いました...

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

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 imagined these waves traveling through a medium called luminiferous aether, which was thought to fill all space. In the early 1800s, Thomas Young showed that light passing through two narrow slits makes an interference pattern. That result fit the wave model much better than the particle model.

James Clerk Maxwell later developed electromagnetic theory and showed that visible light is part of a much larger spectrum of electromagnetic waves. By the end of the nineteenth century, many scientists accepted a split view of the physical world. Matter was described as particles, while electromagnetic radiation was described as waves. These ideas are now called classical mechanics and classical electrodynamics, or classical electromagnetism.

Some experimental results did not fit that classical picture. Scientists first saw them as strange puzzles that might still be solved within the old framework. Those puzzles eventually led to wave-particle duality, a modern idea that links waves and particles at a basic level. This idea replaced the older view.

Electromagnetic radiation matters in chemistry because it can help reveal the energies of electrons in atoms and molecules. It also powers many technologies. Radio waves from a mobile phone, X-rays used by dentists, microwave energy used to cook food, radiant heat from red-hot objects, and the light from a television screen are all forms of electromagnetic radiation. Each of these shows wavelike behavior.

A wave is an oscillation, or repeating motion, that carries energy from one place to another. Rope waves, ripples on water after a pebble falls in, and sound waves from thunder are common examples. In these cases, energy moves through the rope, water, or air while the material itself stays mostly in place. Waves do not have to travel through matter, because electromagnetic waves can move through empty space.

Maxwell showed that electromagnetic waves contain an electric field and a magnetic field that oscillate together. These fields are perpendicular to each other and to the direction the wave travels. In a vacuum, electromagnetic waves move at 2.998 × 10^8 m/s, which is the speed of light, c. Like all waves, they are described by wavelength, frequency, and amplitude.

Wavelength is the distance between two peaks or two troughs. Frequency is the number of wave cycles that pass a point in a given time. Amplitude is the size of the wave’s displacement, which is half the height between a peak and a trough. Amplitude is related to intensity, so for light it affects brightness, and for sound it affects loudness. Wavelength and frequency are linked by the equation λν = speed, so in a vacuum c = λν. As wavelength increases, frequency decreases. Electromagnetic waves span a huge range, from kilometers to picometers, and the full set is called the electromagnetic spectrum.

Measuring Light with Wavelength and Frequency

measuring-light-with-wavelength-and-frequency

the wave nature of light

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

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...

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 light as an electromagnetic wave, including wavelength, frequency, amplitude, the speed of light, and examples from the electromagnetic spectrum.

Measuring Light with Wavelength and Frequency | 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。

Pennsylvania State Academic Standards

9-12

Earth and Space Science

Earth's Systems

3.3.9-12.H

Space Systems

3.3.9-12.B

Weather and Climate

3.3.9-12.E

Physical Science

Waves and Electromagnetic Radiation

3.2.9-12.X

Louisiana Student Standards for Science

Earth Science

Earth’s Place In The Universe

HS-ESS1-1

HS-ESS1-2

Earth’s Systems

HS-ESS2-4

Energy

HS-PS3-3

ohios-learning-standards-and-model-curriculum

Ohio’s Learning Standards and Model Curriculum

Physics

Waves

Light phenomena

Tennessee Academic Standards

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

Waves and Their Applications in Technologies for Information Transfer

PHYS.PS4.7

CHEM1.PS4.1

Virginia  Standards of Learning

HIgh School

ES.2

ES.2.a

Arizona Science Standards

HS+C.P1

HS+C.P1U1.2

CHEM.6

CHEM.6.C

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

9-12.ESS.1.2.b

Next Generation Science Standards

HS-PS4-1

HS-PS4-3

Earth’s Place in the Universe

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.12

SC.912.P.12.7

PHYS.9

PHYS.9.A

PHYS.9.C

PHYS.9.D

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

South Carolina College and Career Ready Science Standards

C-PS4-4

P-PS3-3

P-PS4-1

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.

The Atomic Theory of Matter

The earliest recorded discussion of the basic structure of matter comes from ancient Greek philosophers. Leucippus and Democritus argued that all matter ...

Subatomic Particles

Dalton was only partially correct about the particles that make up matter. All matter is composed of atoms, and atoms are composed of three smaller ...

Elements: Chemical Symbols and Isotopes

A chemical symbol is an abbreviation used to indicate an element or an atom of an element. For example, the symbol for mercury is Hg. The same symbol is ...

Ions and Ionic Charges

In ordinary chemical reactions, the nucleus &mdash; which contains the protons and neutrons of each atom and thus identifies the element &mdash; remains ...

The Periodic Table

As early chemists discovered more elements, they realized that various elements could be grouped by their similar chemical behaviors. One such grouping ...

Atomic Mass

Atoms &mdash; and the protons, neutrons, and electrons that compose them &mdash; are extremely small. For example, a carbon atom weighs less than 2 ...

Molar Mass

The identity of a substance is defined not only by the types of atoms or ions it contains but by the quantity of each type of atom or ion. For example, ...

Periodic Classification of the Elements

The periodic table arranges atoms based on increasing atomic number so that elements with the same chemical properties recur periodically. When their ...

Types of Chemical Bonds

Chemical bonding theories were pioneered by American chemist Gilbert&#xA0;N. Lewis. He developed a model called the Lewis model to explain the type and ...

Ionic Bonding and Electron Transfer

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The Born-Haber Cycle

Lattice Energy&#xA0;

An ionic compound is stable because of the electrostatic attraction between its positive and negative ions. The lattice energy of a ...

trends-in-lattice-energy-ion-size-and-charge

Trends in Lattice Energy: Ion Size and Charge

An ionic compound is stable because of the electrostatic attraction between its positive and negative ions. The lattice energy of a compound is a measure ...

Covalent Bonding and Lewis Structures

Compared to ionic bonds, which results from the transfer of electrons between metallic and nonmetallic atoms, covalent bonds result from the mutual ...

Electronegativity

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Electronegativity values of ...

bond-polarity-dipole-moment-and-percent-ionic-character

Bond Polarity, Dipole Moment, and Percent Ionic Character

Bond Polarity

The absolute value of the difference in electronegativity (&Delta;EN) of two bonded atoms provides a rough measure of the polarity to be ...

lewis-structures-of-molecular-compounds-and-polyatomic-ions

Lewis Structures of Molecular Compounds and Polyatomic Ions

To draw Lewis structures for complicated molecules and molecular ions, it is helpful to follow a step-by-step procedure as outlined:


	Determine the ...

Bond Energies and Bond Lengths

Stable molecules exist because covalent bonds hold the atoms together. The strength of a covalent bond is measured by the energy required to break it, ...

Bonding in Metals

Metallic bonds are formed between two metal atoms. A simplified model to describe metallic bonding has been developed by Paul Dr&#xFC;de called the ...

Model basic atomic structure and relate an element's atomic structure to its bonding, reactivity, and placement on the Periodic Table.

IPC.7.A

physical-and-chemical-properties-of-matter

Physical and Chemical Properties of Matter

The characteristics that enable us to distinguish one substance from another are called properties.

Physical Properties of Matter

A physical property is ...

atomic-radii-and-effective-nuclear-charge

Atomic Radii and Effective Nuclear Charge

The elements in groups of the periodic table exhibit similar chemical behavior. This similarity occurs because the members of a group have the same number ...

Ionic Radii

Ionic radius is the measure used to describe the size of an ion. A cation always has fewer electrons and the same number of protons as the parent atom; it ...

Ionization Energy

The amount of energy required to remove the most loosely bound electron from a gaseous atom in its ground state is called its first ionization energy ...

Electron Affinity

The electron affinity (EA) is the energy change for adding an electron to a gaseous atom to form an anion (negative ion).



This process can be either ...

Alkali Metals

Group 1 elements are soft and shiny metallic solids. They are malleable, ductile, and good conductors of heat and electricity. The melting points of the ...

Use patterns within the Periodic Table to predict the relative physical and chemical properties of elements.

IPC.7.B

Science concepts. The student knows that relationships exist between the structure and properties of matter. The student is expected to:

Measuring Light with Wavelength and Frequency

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