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

Het licht van de zon, de magnetrons die worden gebruikt om voedsel te koken en de radiogolven die worden uitgezonden door wifi-routers zijn allemaal voorbeelden van elektromagnetische straling. Elektromagnetische straling is de overdracht van energie die afkomstig is van de beweging van elektrisch geladen deeltjes. Deze beweging creëert loodrecht oscillerende elektrische en magnetische velden die zich door de ruimte verspreiden in de vorm van golven.Net als alle golven worden elektromagnetische golven gekenmerkt door hun amplitude, golflengte en frequentie. De piekamplitude is de afstand van de middellijn tot de piek of dal van een golf. Het bepaalt de intensiteit van de golf.De amplitude van zichtbaar licht is bijvoorbeeld gerelateerd aan de helderheid;hoe groter de amplitude, hoe helderder of intenser het licht. De golflengte is de afstand tussen identieke punten op aangrenzende golven, zoals opeenvolgende pieken of dalen;het wordt gesymboliseerd door de Griekse letter lambda. Elektromagnetische straling kan worden ingedeeld op golflengte, die kan variëren van kilometers tot picometers.Het golflengtebereik van zichtbaar licht is bijvoorbeeld ongeveer 400 tot 750 nanometer, wat overeenkomt met respectievelijk violet en rood licht. De frequentie, die wordt gesymboliseerd door de Griekse letter nu, is het aantal golfcycli dat in één seconde door een referentiepunt gaat en wordt gemeten in hertz of cycli per seconde. De golflengte is de breedte van één cyclus.De snelheid van een golf is het product van zijn frequentie en golflengte. Daarom is de frequentie van een golf recht evenredig met de snelheid waarop de golf voortbeweegt. Het is echter omgekeerd evenredig met de golflengte van de golf.Daarom hebben golven met lange golflengten, zoals radiogolven, lage frequenties. Deze golven zijn minder energetisch dan golven met hoge frequenties en korte golflengten, zoals gammastraling.

de golfaard van licht

De aard van licht is al sinds de oudheid een onderwerp van onderzoek. Isaac Newton voerde in de zeventiende eeuw experimenten uit met lenzen en prisma's en kon aantonen dat wit licht bestaat uit de afzonderlijke kleuren van de regenboog samen. Newton legde zijn bevindingen op het gebied van de optica uit in termen van een ‘corpusculair’ beeld van licht, waarin licht was samengesteld uit stromen uiterst kleine deeltjes die met hoge snelheid voortbewogen volgens de bewegingswetten van Newton. 
 Anderen uit de zeventiende eeuw, zoals Christiaan Huygens, hadden aangetoond dat optische verschijnselen zoals reflectie en breking net zo goed konden worden verklaard in termen van licht als golven die met hoge snelheid door een medium reizen dat ‘lichtgevende ether’ wordt genoemd en waarvan men dacht dat het alle lichtgevende ethers doordrong. ruimte. In het begin van de negentiende eeuw demonstreerde Thomas Young dat licht dat door nauwe, dicht bij elkaar gelegen spleten viel, interferentiepatronen produceerde die niet verklaard konden worden in termen van Newtoniaanse deeltjes, maar wel gemakkelijk verklaard konden worden in termen van golven. Later in de negentiende eeuw, nadat James Clerk Maxwell zijn theorie over elektromagnetische straling ontwikkelde en aantoonde dat licht het zichtbare deel was van een enorm spectrum van elektromagnetische golven, raakte de deeltjesvisie van licht volledig in diskrediet. 

 Tegen het einde van de negentiende eeuw beschouwden wetenschappers het fysieke universum als een grofweg bestaande uit twee afzonderlijke domeinen: materie die bestaat uit deeltjes die bewegen volgens de bewegingswetten van Newton, en elektromagnetische straling die bestaat uit golven die vallen binnen de vergelijkingen van Maxwell. Tegenwoordig worden deze domeinen klassieke mechanica en klassieke elektrodynamica (of klassiek elektromagnetisme) genoemd. Hoewel er enkele natuurkundige verschijnselen waren die niet binnen dit raamwerk konden worden verklaard, hadden wetenschappers destijds zo veel vertrouwen in de algehele deugdelijkheid van dit raamwerk dat ze deze aberraties beschouwden als raadselachtige paradoxen die uiteindelijk op de een of andere manier binnen dit raamwerk zouden worden opgelost. Deze paradoxen leidden tot een eigentijds raamwerk dat deeltjes en golven nauw met elkaar verbindt op een fundamenteel niveau dat golf-deeltjes dualiteit wordt genoemd en dat de klassieke visie heeft achterhaald. 

 Zichtbaar licht en andere vormen van elektromagnetische straling spelen een belangrijke rol in de chemie, omdat ze kunnen worden gebruikt om de energieën van elektronen in atomen en moleculen af te leiden. Een groot deel van de moderne technologie is gebaseerd op elektromagnetische straling. Radiogolven van een mobiele telefoon, röntgenstralen die door tandartsen worden gebruikt, de energie die wordt gebruikt om voedsel in uw magnetron te bereiden, de stralingswarmte van gloeiend hete voorwerpen en het licht van uw televisiescherm zijn vormen van elektromagnetische straling die alle golfachtig gedrag vertonen. 
 <h4>Golven</h4> 
 Een golf is een oscillatie of periodieke beweging die energie van het ene punt in de ruimte naar het andere kan transporteren. Veelvoorkomende voorbeelden van golven zijn overal om ons heen te vinden. Door het uiteinde van een touw te schudden, wordt energie van je hand naar het andere uiteinde van het touw overgebracht, als je een steentje in een vijver laat vallen, rimpelen de golven langs het wateroppervlak naar buiten, en de uitzetting van de lucht die gepaard gaat met een blikseminslag genereert geluidsgolven (donder). die enkele kilometers naar buiten kunnen reizen. In elk van deze gevallen wordt kinetische energie overgedragen via materie (het touw, water of lucht), terwijl de materie in wezen op zijn plaats blijft. 

 Golven hoeven niet beperkt te worden tot het reizen door materie. Zoals Maxwell aantoonde, bestaan elektromagnetische golven uit een elektrisch veld dat oscilleert in de pas met een loodrecht magnetisch veld, die beide loodrecht staan op de voortbewegingsrichting. Deze golven kunnen door een vacuüm reizen met een constante snelheid van 2,998 x 108 m/s, de snelheid van het licht (aangegeven met c). 

 Alle golven, inclusief vormen van elektromagnetische straling, worden gekenmerkt door een golflengte (aangeduid met λ, de Griekse kleine letter lambda), een frequentie (aangeduid met ν, de Griekse kleine letter nu) en een amplitude. 

 De golflengte is de afstand tussen twee opeenvolgende pieken of dalen in een golf (gemeten in meters in het SI-systeem). Elektromagnetische golven hebben golflengten die binnen een enorm bereik vallen: er zijn golflengten van kilometers (103 m) tot picometers (10-12 m) waargenomen. De frequentie is het aantal golfcycli dat in een bepaalde tijdsduur een bepaald punt in de ruimte passeert (in het SI-systeem wordt dit gemeten in seconden). Een cyclus komt overeen met één volledige golflengte. De eenheid voor frequentie, uitgedrukt als cycli per seconde [s−1], is de hertz (Hz). Gemeenschappelijke veelvouden van deze eenheid zijn megahertz (1 MHz = 1 × 106 Hz) en gigahertz (1 GHz = 1 × 109 Hz). 

 De amplitude komt overeen met de grootte van de verplaatsing van de golf, en dit komt overeen met de helft van de hoogte tussen de pieken en dalen. De amplitude is gerelateerd aan de intensiteit van de golf, die voor licht de helderheid is, en voor geluid de luidheid. Het product van de golflengte (λ) van een golf en zijn frequentie (ν), λν, is de snelheid van de golf. Voor elektromagnetische straling in een vacuüm is de snelheid dus gelijk aan de fundamentele constante c: 

 <img alt="Eq1" src="https://www.jove.com/files/core/CDNSource/lessons/974/974_Equations-01.png" style="height: 40px;"> Golflengte en frequentie zijn omgekeerd evenredig: naarmate de golflengte toeneemt, neemt de frequentie af. Het elektromagnetische spectrum is het bereik van alle soorten elektromagnetische straling.

De golfaard van licht

The nature of light has been a subject of inquiry since antiquity. In the seventeenth century, Isaac Newton performed experiments with lenses and prisms ...

Education

JoVE Core

Chemistry

Scheikunde

Eén

Electronic Structure of Atoms

Elektronische structuur van atomen

KEY TERMS AND CONCEPTS

BELANGRIJKE TERMEN EN CONCEPTEN

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 Chemistry brings general chemistry concepts to life using concise and easy-to-understand animated video lessons. Plus, in the scientist-in-action videos, we demonstrate classical and original research experiments performed in today's laboratories worldwide.

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 ...

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The Periodic Table

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Atomic Mass

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Molar Mass

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Periodic Classification of the Elements

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Types of Chemical Bonds

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The Born-Haber Cycle

Lattice Energy&#xA0;

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Trends in Lattice Energy: Ion Size and Charge

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Covalent Bonding and Lewis Structures

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Electronegativity

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Electronegativity values of ...

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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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