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

태양의 빛, 음식을 요리하는 데 사용되는 전자파 와이파이 라우터에서 방출하는 전파는 모두 전자기 복사의 예입니다. 전자기 복사는 전기적으로 전하를 띤 입자의 운동에서 발생하는 에너지의 전달입니다. 이런 운동에 의해 파동의 형태로 수직으로 진동하는 전기장과 자기장이 공간으로 퍼져 나갑니다.

모든 파장과 마찬가지로 전자기파도 진폭, 파장, 진동수로 특징지어집니다. 최대 진폭은 진동의 중심에서 마루 또는 골까지의 거리입니다. 이 값은 파동의 세기를 결정합니다.

예를 들어 가시광선의 진폭은 밝기와 관련됩니다. 진폭이 클수록 밝거나 강렬한 빛입니다. 파장은 연속적인 마루나 골과 같이 인접한 파장에서 동일한 점 사이의 거리입니다.

파장은 그리스 문자 람다 기호로 표시됩니다. 전자기 복사는 파장에 따라 분류될 수 있으며 파장은 킬로미터에서 피코미터까지 범위가 넓습니다. 예를 들어 가시광선의 파장 범위는 약 400 에서 750나노미터이며 이는 각각 보랏빛과 적색 빛에 해당합니다.

그리스 문자 뉴 로 표시되는 진동수는 1초 만에 기준점을 통과하는 파동 주기의 횟수이며 헤르츠, 즉 초당 사이클로 측정됩니다. 파장은 한 사이클의 폭입니다. 파동의 속도는 진동수와 파장의 곱입니다.

따라서 파동의 진동수는 파동이 이동하는 속도에 정비례합니다. 그러나 파동의 파장에는 반비례합니다. 따라서 라디오파와 같이 파장이 긴 파동은 진동수가 낮습니다.

이런 파동은 감마선과 같이 진동수가 높고 파장이 짧은 파동에 비해 에너지가 작습니다.

빛의 파동적 본질

빛의 본질은 고대부터 탐구의 대상이었습니다. 17세기에 아이작 뉴턴(Isaac Newton)은 렌즈와 프리즘을 사용하여 실험을 수행하여 백색광이 무지개의 개별 색상이 결합되어 구성된다는 것을 입증할 수 있었습니다. 뉴턴은 빛이 뉴턴의 운동 법칙에 따라 고속으로 이동하는 극도로 작은 입자의 흐름으로 구성되어 있다는 빛의 "미립자" 관점에서 자신의 광학적 발견을 설명했습니다.

크리스티안 호이겐스(Christiaan Huygens)와 같은 17세기의 다른 사람들은 반사 및 굴절과 같은 광학 현상이 빛의 관점에서 빛의 관점에서 모든 것에 스며드는 것으로 생각되는 "luminiferous aether"라는 매체를 통해 고속으로 이동하는 파동으로 똑같이 잘 설명될 수 있음을 보여주었습니다. 19세기 초, 토마스 영(Thomas Young)은 좁고 촘촘한 슬릿을 통과하는 빛이 뉴턴 입자로는 설명할 수 없지만 파동으로는 쉽게 설명할 수 있는 간섭 패턴을 생성한다는 것을 입증했습니다. 19세기 후반 제임스 클러크 맥스웰(James Clerk Maxwell)이 전자기 복사 이론을 개발하고 빛이 광범위한 전자기파 스펙트럼의 가시적 부분임을 보여준 후, 빛의 입자 관점은 완전히 신뢰받지 못하게 되었습니다.

19세기 말까지 과학자들은 물리적 우주가 대략 두 개의 개별 영역, 즉 뉴턴의 운동 법칙에 따라 움직이는 입자로 구성된 물질과 맥스웰 방정식에 의해 지배되는 파동으로 구성된 전자기 복사로 구성되어 있다고 생각했습니다. 오늘날 이러한 영역은 고전역학과 고전전기역학(또는 고전 전자기학)으로 불립니다. 이 프레임워크 내에서 설명할 수 없는 몇 가지 물리적 현상이 있었지만 당시 과학자들은 이 프레임워크의 전반적인 건전성에 대해 너무나 확신을 갖고 있었기 때문에 이러한 수차를 궁극적으로 이 프레임워크 내에서 어떻게든 해결될 수수께끼의 역설로 여겼습니다. 이러한 역설은 파동-입자 이중성이라는 기본 수준에서 입자와 파동을 밀접하게 연결하는 현대적인 프레임워크로 이어졌으며, 이는 고전적인 관점을 대체했습니다.

가시광선과 기타 형태의 전자기 방사선은 원자와 분자 내의 전자 에너지를 추론하는 데 사용될 수 있기 때문에 화학에서 중요한 역할을 합니다. 현대 기술의 대부분은 전자기 복사를 기반으로 합니다. 예를 들어, 휴대전화의 전파, 치과 의사가 사용하는 엑스레이, 전자레인지에서 음식을 조리하는 데 사용되는 에너지, 뜨겁게 달궈진 물체에서 나오는 복사열, 그리고 텔레비전 화면에서 나오는 빛은 모두 파동 같은 특성을 보이는 전자기 방사선의 형태입니다.

파동

파동은 우주의 한 지점에서 다른 지점으로 에너지를 전달할 수 있는 진동 또는 주기적인 움직임입니다. 파동의 일반적인 예는 우리 주변에 있습니다. 밧줄 끝을 흔들면 손에서 밧줄의 다른 끝으로 에너지가 전달되고, 연못에 자갈을 떨어뜨리면 물 표면을 따라 파동이 퍼져나가며, 번개와 함께 발생하는 공기의 팽창은 몇 마일까지 퍼져나갈 수 있는 음파(천둥)를 생성합니다. 각각의 경우 운동 에너지는 물질(로프, 물 또는 공기)을 통해 전달되는 반면 물질은 본질적으로 제자리에 남아 있습니다.

파동은 물질을 통과하여 이동하도록 제한될 필요가 없습니다. 맥스웰이 보여준 것처럼 전자기파는 수직 자기장에 맞춰 진동하는 전기장으로 구성되며, 두 자기장은 모두 이동 방향에 수직입니다. 이 파동은 빛의 속도(c로 표시)인 2.998 × 108m/s의 일정한 속도로 진공을 통과할 수 있습니다.

전자기 방사선의 형태를 포함한 모든 파동은 파장(λ로 표시, 그리스 소문자 람다), 주파수(ν로 표시, 그리스 소문자 nu) 및 진폭으로 특징지어집니다.

파장은 파동의 두 연속 최고점 또는 최저점 사이의 거리입니다(SI 시스템에서 미터로 측정). 전자기파는 킬로미터(103m)에서 피코미터(10-12m)에 이르는 엄청난 범위의 파장을 가지고 있습니다. 주파수는 지정된 시간 동안 공간의 지정된 지점을 통과하는 파동 주기의 수입니다(SI 시스템에서는 초 단위로 측정됨). 사이클은 하나의 완전한 파장에 해당합니다. 초당 사이클 [s^−1]로 표시되는 주파수 단위는 헤르츠(Hz)입니다. 이 단위의 공배수는 메가헤르츠(1MHz = 1 × 10^6Hz) 및 기가헤르츠(1GHz = 1 × 10^9Hz)입니다.

진폭은 파동의 변위 크기에 해당하며, 이는 최고점과 최저점 사이 높이의 1/2에 해당합니다. 진폭은 파동의 강도와 관련이 있는데, 빛의 경우 밝기가 되고 소리의 경우 소리의 크기가 됩니다. 파동의 파장(λ)과 주파수(ν)의 곱인 λν는 파동의 속도입니다. 따라서 진공에서의 전자기 복사의 경우 속도는 기본 상수 c와 같습니다.

<img alt="Eq1" src="https://www.jove.com/files/core/CDNSource/lessons/974/974_Equations-01.png" style="height: 40px;" />

파장과 주파수는 반비례합니다. 즉, 파장이 증가하면 주파수는 감소합니다. 전자기 스펙트럼은 모든 유형의 전자기 방사선의 범위입니다.

이 문서는 에서 발췌되었습니다 <a href="https://openstax.org/books/chemistry-2e/pages/6-1-electromagnetic-energy">Openstax, Chemistry 2e, Section 6.1: Electromagnetic Energy.</a>

빛의 본질은 고대부터 탐구의 주제였습니다. 17 세기에 아이작 뉴턴은 렌즈와 프리즘으로 실험을 수행했습니다.

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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

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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

Ions are atoms or molecules bearing an electrical charge. A cation (a positive ion) forms when a neutral atom loses one or more electrons from its valence ...

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

Whether a bond is nonpolar or polar covalent is determined by a property of the bonding atoms called electronegativity.&#xA0;

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 ...

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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