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

지구 궤도를 도는 위성을 생각해 보십시오. 태양과의 거리는 1.5 X 1011 미터입니다. 태양은 3.8 X 1026 와트의 평균 전력 출력으로 방출됩니다.
태양열 집열 패널의 총 면적이 20제곱미터인 경우 태양 전지판에 가해지는 복사 압력과 그로 인한 힘은 얼마입니까?
태양 복사의 강도는 단위 면적당 평균 태양 에너지와 같습니다. 따라서 위성에서의 값은 1.3 X 10 3 미터 제곱 당와트입니다.
태양 전지판이 모든 입사 태양광을 완전히 흡수한다고 가정하면 태양 전지판의 복사 압력은 빛의 속도에 대한 태양 복사 강도와 같으며, 이는 4.3 X 10-6 제곱미터당 뉴턴입니다.
복사력은 복사 압력과 태양 전지판의 면적의 곱입니다. 그 값은 8.6 X 10-5뉴턴으로 계산됩니다.

<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">https://openstax.org/books/university-physics-volume-2/pages/16-4-momentum-and-radiation-pressure</a>; 섹션 16.4; 719–721쪽.</li>
	<li>Young, H.D 및 Freedman, RA (2012). 현대 물리학을 가진 대학 물리학. 샌프란시스코, 캘리포니아 : 피어슨; 섹션 32.4; 페이지 1068-1069.</li>
</ol>

방사선 압력: 문제 해결

전자파가 완벽하게 흡수하는 표면에 가해지는 복사압은 파동의 에너지 밀도와 같습니다. 전자기파가 표면에 완전히 흡수되면 파동의 운동량도 표면으로 전달됩니다. 운동량이 전파 방향에 수직인 흡수 표면으로 전달되는 속도는 표면에 가해지는 힘과 같습니다.

운동량 전달률의 평균값을 흡수 면적으로 나눈 값은 파동에 의한 단위 면적당 평균 힘 또는 복사압을 나타냅니다. 금속 표면과 같이 재료가 완벽하게 반사되고 입사가 표면의 법선을 따르는 경우 반사 시 운동량 방향이 반전되기 때문에 가해지는 압력은 두 배가 됩니다.

햇빛은 지구에서보다 태양 내부에서 훨씬 더 강한 복사압을 발휘합니다. 태양보다 훨씬 더 질량이 크고 밝은 별 내부의 복사압은 너무 높아서 내부 가스압력을 크게 증가시켜 이 별들이 자체 중력으로 인해 붕괴되는 것을 방지합니다. 때로는 별의 복사압이 바로 근처에 있는 물질에 큰 영향을 미칠 수 있습니다.

복사압은 혜성의 출현을 포함하여 관측된 다른 많은 천문 현상을 설명하는 역할을 합니다. 혜성이 태양에 접근하면 따뜻해지고 표면이 증발하기 시작합니다. 일부 가스와 먼지는 혜성을 떠날 때 꼬리를 형성합니다. 혜성에는 두 개의 꼬리가 있습니다. 첫 번째는 주로 이온화된 가스로 구성된 이온 꼬리입니다. 이 이온은 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. 비록 아주 작지만 이 압력은 먼지 꼬리가 혜성의 경로에서 벗어나게 할 만큼 강력합니다.

완벽하게 흡수되는 표면에 전자기파에 의해 가해지는 복사 압력은 파동의 에너지 밀도와 같습니다. 파도의 기세는 ...

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 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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Uniform Circular Motion

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Light as Energy

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Nuclear Fusion

The process of converting very light nuclei into heavier nuclei is also accompanied by the conversion of mass into large amounts of energy, a process ...

First Law of Thermodynamics

The First Law of Thermodynamics states that energy cannot be created or destroyed, only transformed. This can be demonstrated within a classic food web ...

Energy Dynamics

The Food Chain
Energy is one of the most important abiotic factors in an ecosystem and organisms in an ecosystem are connected by the flow of energy and ...

Use models to illustrate how the sun produces energy.

ESS.EES.1.3

Radiation: Applications

The average temperature of Earth is the subject of much current discussion. Earth is in radiative contact with both the Sun and dark space; it receives ...

What is Weather?

Overview

Weather refers to the current state of atmospheric conditions at a specific time and place. Weather is temporary and is influenced by the ...

What is Climate?

Climate refers to the prevailing weather conditions in a specific area over an extended period. As the saying goes, &#8220;Climate is what you expect. ...

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Absorption of Radiation

The rate of heat transfer by emitted radiation is described by the Stefan-Boltzmann law of radiation:

where &#963; is the Stefan-Boltzmann constant, a ...

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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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