Name: radiation pressure in light and comets
Uploaded: 2023-04-30T12:46:50.000Z
Duration: 1 min 20 s
Channel: JoVE

K12 Standards

Pennsylvania State Academic Standards

9-12

Earth and Space Science

Earth's Systems

3.3.9-12.H

Momentum And Radiation Pressure

전자기파는 우주를 여행하는 동안 추진력을 전달합니다. 해당 운동량 밀도는 Poynting 벡터 크기와 빛의 속도로 표현됩니다.
짧은 시간 간격으로 한 지역을 통과하는 파동이 차지하는 부피를 대체함으로써, 단위 면적당 운동량 유량을 얻을 수 있다.
단위 면적당 운동량 전달의 평균 속도는 Poynting 벡터의 평균값을 강도로 대체하여 구합니다.
운동량의 전달로 인해 전자기파는 방사선 압력으로 알려진 표면에 압력을 가합니다.
이제 운동량의 평균 변화율은 평균 힘과 같고 단위 면적당 힘은 복사 압력입니다.
따라서 복사 압력은 파동의 강도에 정비례합니다.
표면이 전자기파를 완벽하게 흡수하면 해당 운동량도 표면으로 완전히 전달됩니다.
완벽하게 반사되는 표면의 경우 운동량 변화가 두 배가 됩니다. 따라서 복사 압력도 두 배가 됩니다.

<ol>
	<li>오픈스택스. (2019). 대학 물리학 Vol. 2. [웹 버전]. 원본 주소 <a href="https://openstax.org/books/university-physics-volume-2/pages/16-4-momentum-and-radiation-pressure">16.4 Momentum and Radiation Pressure - University Physics Volume 2 | 오픈스택스</a></li>
</ol>

운동량과 방사선 압력

전자기파를 흡수하는 물체는 파동이 전파되는 방향으로 힘을 받게 됩니다. 이 힘은 전자기파가 운동량을 포함하고 전달하기 때문에 발생합니다. 힘은 물체에 가해지는 파동의 복사압을 설명합니다. 맥스웰의 예측은 1903년 니콜스와 헐에 의해 비틀림 저울로 복사압을 정밀하게 측정함으로써 확인되었습니다. 측정 장비에는 유리 용기 내부에 보관된 섬유에 매달린 거울이 있습니다. Nichols와 Hull은 거울 중 하나에 빛을 비추어 거울이 약간 측정 가능한 편향을 얻었습니다. 측정된 편향으로부터 이것은 거울에 가해지는 불균형한 힘을 계산하고 예측된 힘 값과 일치하는 것을 얻었습니다. 완벽하게 흡수되는 표면에 전자기파가 가하는 복사 압력은 파동의 에너지 밀도와 동일한 것으로 나타납니다. 물질이 완벽하게 반사하고 전자기파가 표면에 수직으로 입사한다고 가정합니다. 이 경우, 반사되면 운동량의 방향이 바뀌기 때문에 가해지는 압력은 두 배로 커집니다.

복사압력은 혜성의 출현을 포함하여 관측된 많은 천문 현상을 설명하는 역할을 합니다. 혜성이 태양에 접근하면 따뜻해지고, 얼어붙은 가스와 암석, 먼지 입자로 구성된 표면이 증발합니다. 혜성의 혼수상태는 가스와 먼지로 구성된 주변의 흐릿한 영역입니다. 일부 가스와 먼지는 혜성을 떠날 때 꼬리를 형성합니다. 이온 꼬리는 주로 이온화된 가스로 구성됩니다. 이러한 이온은 태양에서 방출되는 연속적인 하전 입자 흐름인 태양풍과 전자기적으로 상호 작용합니다. 이온화된 가스에 대한 태양풍의 힘은 이온 꼬리가 거의 항상 태양으로부터 직접 멀어지는 방향을 향할 정도로 강력합니다. 두 번째 꼬리는 먼지 입자로 구성되어 있습니다. 먼지 꼬리는 전기적으로 중성이므로 태양풍과 상호 작용하지 않습니다. 그러나 이 꼬리는 태양빛에 의해 생성되는 복사압의 영향을 받습니다. 상대적으로 작지만 이 압력은 먼지 꼬리가 혜성의 경로에서 벗어나게 할 만큼 강력합니다.

전자기파를 흡수하는 물체는 파동이 전파되는 방향으로 힘을 받게 됩니다. 이 힘은 ...

Education

교육

JoVE Core

Physics

물리학

Unit 1

제1단원

Electromagnetic Waves

전자기파

KEY TERMS AND CONCEPTS

주요 용어 및 개념

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 mirrors shifted slightly. From that tiny deflection, they calculated the unbalanced force and found agreement with the predicted value.

The size of the pressure depends on the surface. For a perfectly absorbing surface, the radiation pressure equals the energy density of the wave. For a perfectly reflecting surface with the wave hitting straight on, the pressure is twice as large because the light reverses momentum when it reflects.

Radiation pressure also helps explain comet tails. When a comet nears the Sun, it warms up and releases frozen gases, rock, and dust. This forms a coma, which is the hazy cloud around the comet, and it can also create tails.

The ion tail is made mostly of ionized gases. These ions interact with the solar wind, a stream of charged particles from the Sun, and the tail usually points away from the Sun. The dust tail is different. It contains neutral dust, so it does not respond to the solar wind. Instead, sunlight’s radiation pressure pushes the dust tail away from the comet’s path.

Radiation Pressure in Light and Comets

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...

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the electromagnetic spectrum

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plane electromagnetic waves i

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plane electromagnetic waves ii

Faraday’s Law in a Plane Wave

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propagation speed of electromagnetic waves

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electromagnetic waves in matter

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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 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 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...

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key terms and concepts

Explore how light carries momentum, creates radiation pressure, and was measured by Nichols and Hull. See how it helps shape comet tails.

Radiation Pressure in Light and Comets | 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.

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-ESS2-1

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.

new-york-state-science-learning-standards

New York State Science Learning Standards

HS. Waves and Electromagnetic Radiation

HS-PS4-4.

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3.3.9-12.I

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3.3.9-12.K

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3.3.9-12.L

Radiation Pressure in Light and Comets

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