Name: radiation pressure in light and space
Uploaded: 2023-09-18T17:11:21.000Z
Duration: 1 min 9 s
Channel: JoVE

K12 Standards

north-carolina-k-12-science-standard-course-of-study

NC K-12 Science Standard Course of Study

9-12

Earth and Environmental Science

Earth's Place in the Universe

ESS.EES.1.4

Radiation Pressure: Problem Solving

Weźmy pod uwagę satelitę krążącego wokół Ziemi. Jego odległość od Słońca wynosi 1,5 X 1011 metrów. Słońce promieniuje ze średnią mocą wyjściową 3,8 X 1026 watów.
Jeśli jego panele słoneczne mają łączną powierzchnię 20 metrów kwadratowych, jakie byłoby ciśnienie promieniowania na panelach słonecznych i siła z niego wynikająca?
Intensywność promieniowania słonecznego jest równa średniej mocy słonecznej na jednostkę powierzchni. Jego wartość w satelicie wynosi więc 1,3 X 103 watów na metr kwadratowy.
Zakładając, że panele słoneczne całkowicie pochłaniają całe padające światło słoneczne, ciśnienie promieniowania na panelach słonecznych jest równe natężeniu promieniowania słonecznego z prędkością światła, która wynosi 4,3 X 10-6 niutonów na metr kwadratowy.
Siła promieniowania jest iloczynem ciśnienia promieniowania i powierzchni paneli słonecznych. Jego wartość oblicza się na 8,6 X 10-5 niutonów.

<ol>
	<li>Protokół OpenStax. (2019). Fizyka uniwersytecka Vol. 2. [Wersja internetowa]. Pobrane z <a href="https://openstax.org/books/university-physics-volume-2/pages/16-4-momentum-and-radiation-pressure">https://openstax.org/books/university-physics-volume-2/pages/16-4-momentum-and-radiation-pressure</a>; sekcja 16.4; strony 719–721.</li>
	<li>Young, H.D i Freedman, R.A. (2012). Fizyka uniwersytecka z fizyką współczesną. San Francisco, Kalifornia: Pearson; sekcja 32.4; strony 1068-1069.</li>
</ol>

ciśnienie promieniowania: rozwiązywanie problemów

Ciśnienie promieniowania wywierane przez falę elektromagnetyczną na doskonale absorbującą powierzchnię jest równe gęstości energii fali. Pęd fali zostaje również przeniesiony na powierzchnię, gdy fala elektromagnetyczna zostanie przez nią całkowicie pochłonięta. Szybkość, z jaką pęd jest przekazywany na powierzchnię pochłaniającą, prostopadłą do kierunku propagacji, jest równa sile działającej na tę powierzchnię.

Średnia wartość szybkości przenoszenia pędu podzielona przez powierzchnię pochłaniającą reprezentuje średnią siłę na jednostkę powierzchni lub ciśnienie promieniowania wywołane falą. Jeśli materiał doskonale odbija światło, np. powierzchnia metalu, a padanie jest wzdłuż normalnej do powierzchni, wówczas wywierane ciśnienie podwaja się, ponieważ po odbiciu kierunek pędu ulega odwróceniu.

Światło słoneczne wywiera znacznie większe ciśnienie promieniowania wewnątrz Słońca niż na Ziemi. Ciśnienie promieniowania wewnątrz gwiazd znacznie masywniejszych i jaśniejszych od Słońca jest tak wysokie, że znacznie zwiększa wewnętrzne ciśnienie gazu, zapobiegając zapadaniu się tych gwiazd pod wpływem ich własnej grawitacji. Czasami ciśnienie promieniowania gwiazd może znacząco wpływać na materię w ich bezpośrednim sąsiedztwie.

Ciśnienie promieniowania odgrywa rolę w wyjaśnianiu wielu innych obserwowanych zjawisk astronomicznych, w tym pojawiania się komet. Kiedy kometa zbliża się do Słońca, nagrzewa się, a jej powierzchnia zaczyna parować. Część gazów i pyłu opuszczając kometę tworzy warkocze. Kometa ma dwa ogony; pierwszy to ogon jonowy, składający się głównie ze zjonizowanych gazów. Jony te oddziałują elektromagnetycznie z wiatrem słonecznym. Siła wiatru słonecznego działającego na zjonizowane gazy jest na tyle duża, że ogon jonowy prawie zawsze jest skierowany bezpośrednio w stronę słońca.

Drugi ogon składa się z cząstek pyłu. Ponieważ ogon pyłowy jest elektrycznie obojętny, nie oddziałuje z wiatrem słonecznym. Jednakże na ogon ten wpływa ciśnienie promieniowania wytwarzanego przez światło słoneczne. Chociaż ciśnienie to jest dość małe, jest wystarczająco silne, aby spowodować przesunięcie ogona pyłowego z ścieżki komety.

Ciśnienie promieniowania: rozwiązywanie problemów

Ciśnienie promieniowania wywierane przez falę elektromagnetyczną na idealnie absorbującą powierzchnię jest równe gęstości energii fali. Pęd fali ...

Education

JoVE Core

Physics

Fizyka

Unit 1

Jednostka 1

Electromagnetic Waves

Fale elektromagnetyczne

KEY TERMS AND CONCEPTS

Kluczowe terminy i pojęcia

radiation pressure in light and space

Radiation pressure is the push that light can exert on matter. When an electromagnetic wave is completely absorbed by a surface, its energy density is transferred as momentum to that surface. The rate of momentum transfer on a surface perpendicular to the wave gives the force, and the force per unit area is the radiation pressure.

A perfectly absorbing surface receives this pressure directly from the incoming wave. If the surface is perfectly reflecting, such as a metal surface, and the light strikes it straight on, the pressure doubles. That happens because the momentum changes direction after reflection.

Radiation pressure is much stronger inside the sun than it is on Earth. In stars that are more massive and brighter than the sun, it can greatly increase the internal gas pressure. This extra pressure helps keep those stars from collapsing under their own gravity.

Radiation pressure also helps explain comet tails. As a comet moves close to the sun, it warms up and its surface begins to evaporate. Gas and dust escape and form tails.

A comet has two tails. The ion tail is made mainly of ionized gas, and it interacts with the solar wind. That force is strong enough that the ion tail usually points directly away from the sun. The dust tail is electrically neutral, so it does not interact with the solar wind. Instead, sunlight pushes on it through radiation pressure, and this small force can make the dust tail bend away from the comet’s path.

Radiation Pressure in Light and Space

electromagnetic waves

Maxwell’s Equations Behind EM Waves

Maxwell’s equations explain how electric and magnetic fields work together to create electromagnetic waves. James Clerk Maxwell brought together the ideas of Oersted, Coulomb, Gauss, and Faraday and built a single theory of electromagnetism. Together with the Lorentz force law, his equations describe the laws of electricity and magnetism. A key part of Maxwell’s work is the symmetry in the equations. Faraday’s law shows that a changing magnetic field produces an electric field. Maxwell added...

generating electromagnetic radiations

Hertz's Spark Gaps and Radio Waves

Heinrich Hertz used sparks and tuned circuits to show that electromagnetic waves could be produced in the lab. Starting in 1887, the German physicist ran experiments that confirmed electromagnetic waves exist and travel at the speed of light. Hertz built an alternating-current RLC circuit. RLC stands for resistor, inductor, and capacitor. The circuit was set to a known resonant frequency and connected to a loop of wire. High voltage across the gap in the loop created sparks. Those sparks gave...

the electromagnetic spectrum

Electromagnetic Waves in Everyday Technology

Electromagnetic waves are grouped by wavelength and frequency. This set of waves is called the electromagnetic spectrum. It includes radio waves, microwaves, infrared, visible light, X-rays, and gamma rays. Radio waves have wavelengths from millimeters to kilometers. They are often used for audio communication, such as radios. In many cases, they come from alternating current in the wires of a broadcast antenna. Radio waves also carry AM and FM radio, cellular phone signals, and TV signals. <br...

electromagnetic wave equation

How Maxwell Linked Light to Waves

Maxwell's equations show how electric and magnetic fields behave in a vacuum, or empty space. They are written as differential equations and describe fields created by source charges, whether the charges are still or moving. These fields also act on a test charge, and its motion can be found with the right boundary conditions. The key question in empty space is what happens when there are no source charges. In the vacuum form of Maxwell's four equations, the first-order partial differential...

plane electromagnetic waves i

Transverse Fields in Electromagnetic Waves

Electromagnetic waves are made of electric and magnetic fields that move through space together. Maxwell's equations predict these waves, and they can travel in free space without a medium. The electric field acts on a stationary charge, while the magnetic field acts on a moving charge. For a wave traveling along the x-axis, the fields are written as Ey(x, t) and Bz(x, t). In free space, there are no free charges or currents, so the charge enclosed and current terms in Maxwell's equations are...

plane electromagnetic waves ii

Faraday’s Law in a Plane Wave

Faraday’s law can be used to link the electric and magnetic fields in a plane electromagnetic wave. Here, the wavefront moves in the x-direction at a constant speed. The goal is to show how the field strengths must be related for the wave to stay consistent with Faraday’s law. To apply the law, a rectangle of width a is placed with its area vector in the positive z-direction. The line integral is taken counterclockwise around the rectangle. One side lies outside the wavefront, so the electric...

propagation speed of electromagnetic waves

propagation-speed-of-electromagnetic-waves

Maxwell’s Equations and Light Speed

Electromagnetic waves follow Ampere’s law when there is no conduction current. A plane wavefront moves in the positive x-direction. To analyze it, a rectangle is placed in the xz-plane with its area vector pointing in the positive y-direction. The line integral around the rectangle is taken counterclockwise. The magnetic field is zero on some sides and perpendicular on others. It is parallel to one side, and that side gives a non-zero contribution to the integral. Because the left side of...

electromagnetic waves in matter

How Light Slows in Materials

Electromagnetic waves can travel through matter as well as through vacuum. Light is one example. It can move through air, water, or glass. When an electromagnetic wave passes through a dielectric medium, the equations that describe it change. In Ampere's law, the permittivity of free space, ε0, is replaced by the permittivity of the dielectric, ε. The vacuum permeability, μ0, is also replaced by the permeability of the medium, μ. The wave speed c in vacuum is then replaced by a lower speed, v,...

energy carried by electromagnetic waves

How EM Waves Transfer Energy

Electromagnetic waves transfer energy through their electric and magnetic fields. This energy can be easy to notice, like the warmth from the summer sun, or harder to feel, like the energy in gamma rays that can damage living cells. The fields in an electromagnetic wave can exert forces on charges in a system. They can move those charges and do work on them. Even if a wave is not absorbed right away, it still carries energy away from its source. If some of the wave energy is absorbed, the...

intensity of electromagnetic waves

Poynting Vector and Light Intensity

The Poynting vector describes the energy flux of an electromagnetic wave. It tells how much energy passes through a unit area in a unit time at a specific moment. For a plane electromagnetic wave moving along the x-axis, the energy flux depends on the peak electric field E0 and the peak magnetic field B0. For high-frequency waves, the energy flux changes very quickly with time. Visible light has a frequency on the order of 10^14 Hz, so its energy flux varies too fast to track directly. Most...

momentum and radiation pressure

Radiation Pressure in Light and Comets

Radiation pressure is the force that electromagnetic waves can exert on matter. It appears because light carries momentum, so an object that absorbs a wave feels a push in the direction the wave travels. This same force helps explain why sunlight can affect small particles in space. Maxwell predicted radiation pressure, and Nichols and Hull confirmed it in 1903. They used a torsion balance with mirrors suspended from a fiber inside a glass container. When they shone light on one mirror, the...

radiation pressure: problem solving

Radiation pressure is the push that light can exert on matter. When an electromagnetic wave is completely absorbed by a surface, its energy density is transferred as momentum to that surface. The rate of momentum transfer on a surface perpendicular to the wave gives the force, and the force per unit area is the radiation pressure. A perfectly absorbing surface receives this pressure directly from the incoming wave. If the surface is perfectly reflecting, such as a metal surface, and the light...

standing electromagnetic waves

Electromagnetic Wave Reflection at Conductors

Electromagnetic waves can reflect from a conductor or a dielectric. When the reflected wave combines with the incoming wave, the result is a standing electromagnetic wave. This is similar to the standing waves formed on a stretched string. To see how this happens, consider a perfect conductor placed in the yz-plane. A linearly polarized electromagnetic wave moving in the negative x-direction strikes the surface. The electric field cannot have a component parallel to the surface of a perfect...

standing waves in a cavity

Electromagnetic Modes in a Microwave Cavity

Electromagnetic waves can form standing patterns inside a cavity. Household microwaves and lasers are common examples of this effect. When two conducting metal plates are placed parallel at the nodal planes, they create a space where standing waves can exist. The cavity between the plates works like a stretched string fixed at x = 0 and x = L. The distance L must be an integer multiple of half a wavelength. The wavelengths that meet this condition have matching frequencies, and each frequency,...

key terms and concepts

Explore how electromagnetic waves transfer momentum, how reflection changes radiation pressure, and why sunlight shapes star balance and comet tails.

Radiation Pressure in Light and Space | JoVE K12

physics

JoVE Core Physics introduces the theory and application of fundamental physics topics, including kinematics, dynamics, fluid mechanics, statics, waves, and acoustics, with concise and easy-to-understand animated videos. Additionally, the scientist-in-action videos demonstrate the application of related concepts in classical and original research experiments performed in today's laboratories worldwide.

Pennsylvania State Academic Standards

Earth and Space Science

Earth's Systems

3.3.9-12.H

Weather and Climate

3.3.9-12.E

Physical Science

Waves and Electromagnetic Radiation

3.2.9-12.V

Louisiana Student Standards for Science

High School

Earth Science

Earth’s Systems

HS-ESS2-4

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

Waves And Their Applications In Technologies For Information Transfer

HS-PS4-1

Virginia  Standards of Learning

HIgh School

PS.7

PS.7.a

Alabama Course of Study Science

Waves and Their Applications in Technologies for Information Transfer

9-12.PS.2.2.e

9-12.P.3.7.c

Florida Department of Education

SC.912.P.10

SC.912.P.10.19

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

South Carolina College and Career Ready Science Standards

P-PS4-4

Earth and Space Science (ESS)

Earth’s Place in the Universe

E-ESS1-2.

E-ESS2-4.

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First Law of Thermodynamics

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Energy Dynamics

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Use models to illustrate how the sun produces energy.

ESS.EES.1.3

Radiation: Applications

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What is Weather?

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What is Climate?

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Explain how Earth's position relative to the sun influences conditions on Earth.

Radiation Pressure in Light and Space

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