Name: wave patterns from light and slits
Uploaded: 2020-09-03T13:38:27.000Z
Duration: 2 min 18 s
Channel: JoVE

K12 Standards

ohios-learning-standards-and-model-curriculum

Ohio’s Learning Standards and Model Curriculum

9-12

Physics

Waves

Wave properties

Interference and Diffraction

Уникальное свойство волн состоит в том, что, когда они взаимодействуют друг с другом, они взаимодействуют таким образом, что результирующая волна имеет либо увеличенную, либо уменьшенную амплитуду. Это явление называется интерференцией. Когда гребни двух волн совпадают, они находятся в фазе"Когда эти волны взаимодействуют, их амплитуды складываются, и возникает волна с увеличенной амплитудой.Это является конструктивной интерференцией. Если две волны не совпадают так что их гребни смотрят в противоположных направлениях, они находятся вне фазы"В этом случае результирующая волна имеет меньшую амплитуду. Это является деструктивной интерференцией.Когда впадина одной волны полностью перекрывается гребнем другой, волны компенсируют друг друга. Дифракция еще одно характерное поведение волн. Возьмите волну в перспективе сверху и представьте, что волна движется к преграде с узким отверстием.Отверстие в преграде по размеру соответствует длине волны. При прохождении волны она огибает углы отверстия и распространяется в разные стороны. Но как будут вести себя волны, когда в преграде есть два или более отверстий?Это можно наблюдать с помощью источника света. Когда свет излучается, волна проходит через пару близко расположенных щелей, и появляются две дифрагированные волны. Эти волны интерферируют друг с другом, создавая узор.Когда две волны проходят одинаковое расстояние, они конструктивно интерферируют. Это наблюдается по появлению яркой линии. На небольшом расстоянии от центра в любом направлении одна волна проходит немного большее расстояние, чем другая волна, и они уже находятся вне фазы"Деструктивная интерференция создает темную область.В зависимости от пройденных волнами расстояний образуется интерференционная картина из чередующихся ярких и темных линий. Этот эксперимент с двумя щелями демонстрирует волновую природу света.

Интерференция и дифракция

Интерференция — характерный феномен, проявляемый волнами. Когда две электромагнитные волны взаимодействуют с совпадающими пиками и желобами, образуется результирующая волна с повышенной амплитудой. Это называется конструктивной интерференцией. В этом случае две взаимодействующие волны находятся в фазе друг с другом. 
 
 В качестве альтернативы, если две волны совпадают и взаимодействуют таким образом, что минимум одной волны совпадает с пиком другой (в разфазной манере), результирующая волна будет отображать гораздо меньшую амплитуду. Это называется деструктивной интерференцией. 
 
 Волны также показывают характерное поведение, называемое дифракцией. Когда луч света проходит через щель размером сопоставимую с длиной волны падающего пучка －луч изгибается (или рассеивается) вокруг щели. Напротив, когда поток частиц проходит через щель, частицы просто выходят через отверстие. 
 
 Далее, когда луч света проходит через пару близко расположенных щелей, отстоящих на расстояние, сравнимое с длиной волны света, от каждой щели образуется круговая волна в процессе дифракции. Эти две волны интерферируют друг с другом, так что на экране, размещенном на небольшом расстоянии от щели, появляется интерференция-узор с чередующимися темными и яркими линиями. 
 
 Яркая линия образуется в центре экрана, так как две волны проходят равное расстояние, чтобы достичь этой точки и конструктивно итерферировать. Когда две волны проходят небольшое расстояние от центра в любом направлении, они проходят немного разные расстояния. Они не в фазе. Когда разница в пройденном расстоянии составляет ровно половину длины волны, они встречаются, производя деструктивную интерференцию. Темные области соответствуют областям, где пики для волны из одной щели совпадают с минимумами для волны из другой щели (деструктивная интерференция), в то время как наиболее яркие области соответствуют областям, где пики для двух волн (или их минимумы) совпадают (конструктивная интерференция). Картина дифракции является неотъемлемым свойством волн и представляет неопровержимые доказательства волновой примоль света.  
 
 Этот текст адаптирован из <a href=""https://openstax.org/books/chemistry-2e/pages/6-1-electromagnetic-energy"">Openstax, Химия 2e, раздел 6.1: Электромагнитная энергия.</a>

Интерференция является характерным явлением, проявляемым волнами. Когда две электромагнитные волны взаимодействуют со своими пиками и впадинами, ...

Education

JoVE Core

Chemistry

Химия

Один

Electronic Structure of Atoms

Электронное строение атомов

KEY TERMS AND CONCEPTS

ОСНОВНЫЕ ТЕРМИНЫ И ПОНЯТИЯ

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 its wavelength, it bends around the opening. A stream of particles passing through a slit does not spread in the same way and simply passes through the aperture. This contrast helps show that light behaves like a wave in this setting.

Diffraction also appears when light passes through two closely spaced slits. Each slit produces circular waves by diffraction. The two waves then interfere and form a pattern of bright and dark lines on a screen behind the slits. The center of the screen is bright because the waves travel the same distance and combine constructively. Farther from the center, the waves travel slightly different distances and become out of phase. When that path difference is one half of a wavelength, destructive interference creates dark bands. The bright and dark regions in this pattern are evidence for the wave nature of light.

Wave Patterns from Light and Slits

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

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

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

See how light creates bright and dark bands through interference and diffraction, and how slit size and wave spacing reveal light’s wave nature.

Wave Patterns from Light and Slits | 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.

Light phenomena

Tennessee Academic Standards

High School

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

Waves and Their Applications in Technologies for Information Transfer

PHYS.PS4.7

Florida Department of Education

Physical Science

SC.912.P.8

SC.912.P.8.3

new-york-state-science-learning-standards

New York State Science Learning Standards

HS. Chemical Reactions

HS-PS1-7.

Kinetic and Potential Energy of a Wave

All forms of waves carry energy; this is directly visualized in nature. For instance, the waves of earthquakes are so intense that they can shake huge ...

Energy and Power of a Wave

The total energy associated with a wavelength is the sum of the potential energy and the kinetic energy. The average rate of energy transfer associated ...

Interference and Superposition of Waves

When two waves of the same nature occur in the same region simultaneously, they result in interference. Interference of waves implies that the net effect ...

Reflection of Waves

When a wave travels from one medium to another, it gets reflected at the boundary of the second medium. A common example of this is when a person yells at ...

Propagation of Waves

When a wave propagates from one medium to another, part of it may get reflected in the first medium, and part of it may get transmitted to the second ...

Standing Waves

Sometimes waves do not seem to move; rather, they just vibrate in place. Unmoving waves can be seen on the surface of a glass of milk kept in a ...

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Modes of Standing Waves - I

A close look at earthquakes provides evidence for the conditions appropriate for resonance, standing waves, and constructive and destructive interference. ...

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Modes of Standing Waves: II

The starting point for expressing the modes of standing waves is understanding the boundary conditions that the waves must follow. The boundary conditions ...

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Sound Waves: Interference

Sound waves can be modeled either as longitudinal waves, wherein the molecules of the medium oscillate around an equilibrium position, or as pressure ...

Interference: Path Lengths

Consider two sources of sound, that may or may not be in phase, emitting waves at a single frequency, and consider the frequencies to be the same.
Two ...

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Sound Waves: Resonance

Resonance is produced depending on the boundary conditions imposed on a wave. Resonance can be produced in a string under tension with symmetrical ...

Interference is a characteristic phenomenon exhibited by waves. When two electromagnetic waves interact with their peaks and troughs coinciding, a ...

Wave properties
• Conservation of energy
• Reflection
• Refraction
• Interference
• Diffraction

Content elaboration: When a wave reaches a barrier or a new medium, a portion of its energy is reflected at the boundary and a portion of the energy passes into the new medium. Some of the energy that passes to the new medium may be absorbed by the medium and transformed to other forms of energy, usually thermal energy, and some continues as a wave in the new medium. Some of the energy may also be dissipated and no longer be part of the wave since it has been transformed into thermal energy or transferred out of the system due to the interaction of the system with surrounding objects. Usually all of these processes occur simultaneously, but the total amount of energy must remain constant. When waves bounce off barriers (reflection), the angle at which a wave approaches the barrier (angle of incidence) equals the angle at which the wave reflects off the barrier (angle of reflection). When a wave travels from a two-dimensional (e.g., surface water, seismic waves) or three-dimensional (e.g., sound, electromagnetic waves) medium into another medium in which the wave travels at a different speed, both the speed and the wavelength of the transferred wave change. Depending on the angle between the wave and the boundary, the direction of the wave can also change, resulting in refraction. The amount of bending of waves around barriers or small openings (diffraction) increases with decreasing wavelength. When the wavelength is smaller than the obstacle or opening, no noticeable diffraction occurs. Standing waves and interference patterns between two sources are included in this topic. As waves pass through a single or double slit, diffraction patterns are created with alternating lines of constructive and destructive interference. The diffraction patterns demonstrate predictable changes as the width of the slit(s), spacing between the slits and/or the wavelength of waves passing through the slits changes.

Photoelectric Effect

When light of a particular wavelength strikes a metal surface, electrons are emitted. This is called the photoelectric effect. The minimum frequency of ...

Electromagnetic Waves

James Clerk Maxwell formulated a single theory combining all the electric and magnetic effects scientists knew during that time, calling the phenomena his ...

The Electromagnetic Spectrum

Electromagnetic waves are categorized according to their wavelengths and frequencies, giving the electromagnetic spectrum. These waves are classified as ...

The Wave Nature of Light

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

dual-nature-of-electromagnetic-em-radiation

Dual Nature of Electromagnetic (EM) Radiation

Electromagnetic (EM) radiation consists of electric and magnetic field components oscillating in planes perpendicular to each other and mutually ...

Light phenomena
• Ray diagrams (propagation of light)
• Law of reflection (equal angles)
• Snell's law
• Diffraction patterns
• Wave-particle duality of light
• Visible spectrum of color

Content elaboration: The path of light waves can be represented with ray diagrams to show reflection and refraction through converging lenses, diverging lenses and plane mirrors. Since light is a wave, the law of reflection applies. Snell's law, $n_{1}sin\theta_{1}=n_{2}sin~\theta_{2},$ quantifies refraction in which n is the index of refraction of the medium and is the angle the wave enters or leaves the medium as measured from the normal line. The index of refraction of a material can be calculated by the equation $n=c/v$, where n is the index of refraction of a material, v is the speed of light through the material, and c is the speed of light in a vacuum. Diffraction patterns of light are addressed, including patterns from diffraction gratings. There are two models of how radiant energy travels through space at the speed of light. One model is that the radiation travels in discrete packets of energy called photons that are continuously emitted from an object in all directions. The energy of these photons is directly proportional to the frequency of the electromagnetic radiation. This particle-like model is called the photon model of light energy transfer. A second model is that radiant energy travels like a wave that spreads out in all directions from a source. This wave-like model is called the electromagnetic wave model of light energy transfer. Strong scientific evidence supports both the particle-like model and wave-like model. Depending on the problem scientists are trying to solve, either the particle-like model or the wave-like model of radiant energy transfer is used. Students are not required to know the details of the evidence that supports either model at this level. Humans can only perceive a very narrow portion of the electromagnetic spectrum. Radiant energy from the sun or a light bulb filament is a mixture of all the colors of light (visible light spectrum). The different colors correspond to different radiant energies. When white light hits an object, the pigments in the object reflect one or more colors in all directions and absorb the other colors.

Wave Patterns from Light and Slits

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