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

تنقل الموجات الكهرومغناطيسية الزخم أثناء السفر عبر الفضاء. يتم التعبير عن كثافة الزخم المقابلة من حيث حجم متجه بوينتينج وسرعة الضوء.
من خلال استبدال الحجم الذي تشغله الموجة التي تمر عبر منطقة في فترة زمنية قصيرة ، يمكن الحصول على معدل تدفق الزخم لكل وحدة مساحة.
يتم الحصول على متوسط معدل نقل الزخم لكل وحدة مساحة عن طريق استبدال متوسط قيمة متجه Poynting بالكثافة.
بسبب نقل الزخم ، تمارس الموجات الكهرومغناطيسية ضغطا على السطح ، يعرف باسم ضغط الإشعاع.
متوسط معدل تغير الزخم يساوي متوسط القوة والقوة لكل وحدة مساحة هو ضغط الإشعاع.
وبالتالي ، فإن ضغط الإشعاع يتناسب طرديا مع شدة الموجة.
إذا كان السطح يمتص الموجة الكهرومغناطيسية تماما ، أيضا نقل الزخم المقابل بالكامل إلى السطح.
بالنسبة لسطح عاكس تماما ، سيكون تغيير الزخم مزدوجا. وبالتالي ، يتضاعف ضغط الإشعاع أيضا.

<ol>
	<li>OpenStax. (2019). جامعة الفيزياء المجلد 2. [نسخة الويب]. تم الاسترجاع من <a href = "https://openstax.org/books/university-physics-volume-2/pages/16-4-momentum-and-radiation-pressure" >16.4 الزخم وضغط الإشعاع - جامعة فيزياء المجلد 2 | أوبن ستاكس</a></li>
</ol>

الزخم والضغط الإشعاعي

<div style="direction:rtl">الجسم الذي يمتص موجة كهرومغناطيسية سيتعرض لقوة في اتجاه انتشار الموجة. تحدث هذه القوة لأن الموجات الكهرومغناطيسية تحتوي على الزخم وتنقله. تمثل القوة ضغط إشعاع الموجة الواقع على الجسم. تم تأكيد تنبؤات ماكسويل في عام 1903 من قبل نيكولز وهال من خلال قياس ضغوط الإشعاع بدقة باستخدام ميزان الالتواء. تحتوي أداة القياس على مرايا معلقة من ألياف محفوظة داخل وعاء زجاجي. حصل نيكولز وهال على انحراف طفيف يمكن قياسه في المرايا من تسليط الضوء على إحداهما. ومن الانحراف المقاس، حسبوا القوة غير المتوازنة على المرآة وحصلوا على اتفاق مع القيمة المتوقعة للقوة. تبين أن ضغط الإشعاع الذي تطبقه الموجة الكهرومغناطيسية على سطح ممتص تمامًا يساوي كثافة طاقة الموجة. لنفترض أن المادة عاكسة تمامًا، وأن الموجات الكهرومغناطيسية تسقط بشكل طبيعي على السطح. وفي هذه الحالة، يكون الضغط المبذول ضعفًا لأن اتجاه الزخم ينعكس عند الانعكاس. يلعب الضغط الإشعاعي دورا في تفسير العديد من الظواهر الفلكية المرصودة، بما في ذلك ظهور المذنبات. عندما يقترب المذنب من الشمس، فإنه يسخن، ويتبخر سطحه المكون من الغازات المتجمدة وجزيئات الصخور والغبار. غيبوبة المذنب هي المنطقة الضبابية المحيطة به والتي تتكون من الغازات والغبار. تشكل بعض الغازات والغبار ذيولًا عندما تغادر المذنب. يتكون الذيل الأيوني بشكل رئيسي من الغازات المتأينة. تتفاعل هذه الأيونات كهرومغناطيسيًا مع الرياح الشمسية، وهي تيار مستمر من الجسيمات المشحونة المنبعثة من الشمس. إن قوة الرياح الشمسية على الغازات المتأينة قوية بما يكفي بحيث يشير الذيل الأيوني دائمًا تقريبًا بعيدًا عن الشمس. يتكون الذيل الثاني من جزيئات الغبار. ولأن الذيل الغباري محايد كهربائيا، فإنه لا يتفاعل مع الرياح الشمسية. ومع ذلك، فإن هذا الذيل يتأثر بالضغط الإشعاعي الناتج عن ضوء الشمس. وعلى الرغم من صغر حجمه نسبيًا، إلا أن هذا الضغط قوي بما يكفي لإزاحة ذيل الغبار عن مسار المذنب.</div>

سيختبر الجسم الذي يمتص موجة كهرومغناطيسية قوة في اتجاه انتشار الموجة. تحدث هذه القوة بسبب ...

Education

JoVE Core

Physics

الفيزياء

Unit 1

الوحدة الأولى

Electromagnetic Waves

الموجات الكهرومغناطيسية

KEY TERMS AND CONCEPTS

المصطلحات والمفاهيم الأساسية

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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plane electromagnetic waves i

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plane electromagnetic waves ii

Faraday’s Law in a Plane Wave

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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

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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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