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

North Carolina 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

Consider a satellite orbiting earth. Its distance from the sun is 1.5 X 1011 meters. The sun radiates with an average power output of 3.8 X 1026 watts.
If its solar collecting panels have a total area of 20 square meters, what would be the radiation pressure on the solar panels and the force due to it?
The intensity of the solar radiation equals the average solar power per unit area. Its value at the satellite is thus 1.3 X 103 watts per meter square.
Assuming that the solar panels completely absorb all the incident sunlight, the radiation pressure on the solar panels equals the solar radiation intensity over the speed of light, which is 4.3 X 10-6 newtons per meter square.
The radiation force is the product of radiation pressure and the area of the solar panels.&#160; Its value is calculated to be 8.6 X 10-5 newtons.

radiation pressure: problem solving

The radiation pressure applied by an electromagnetic wave on a perfectly absorbing surface equals the energy density of the wave. The wave&#39;s momentum also gets transferred to the surface when an electromagnetic wave is entirely absorbed by it. The rate at which momentum is transmitted to an absorbing surface perpendicular to the propagation direction equals the force on the surface.
The average value of the rate of momentum transfer divided by the absorbing area represents the average force per unit area or radiation pressure due to the wave. If the material is perfectly reflecting, such as a metal surface, and the incidence is along the normal to the surface, then the pressure exerted doubles because the momentum direction reverses upon reflection.
Sunlight exerts a far stronger radiation pressure inside the sun than it does on the Earth. Radiation pressure inside stars that are significantly more massive and brighter than the sun is so high that it greatly increases the internal gas pressure, preventing these stars from collapsing due to their own gravity. Sometimes, the radiation pressure of stars can significantly impact the material in their immediate vicinity.
Radiation pressure plays a role in explaining many other observed astronomical phenomena, including the appearance of comets. When a comet approaches the sun, it warms up, and its surface begins to evaporate. Some of the gases and dust form tails when they leave the comet. A comet has two tails; the first is the ion tail, composed mainly of ionized gases. These ions interact electromagnetically with the solar wind. The force of the solar wind on the ionized gases is strong enough that the ion tail almost always points directly away from the sun.
The second tail is composed of dust particles. Because the dust tail is electrically neutral, it does not interact with the solar wind. However, this tail is affected by the radiation pressure produced by the light from the sun. Although quite small, this pressure is strong enough to cause the dust tail to be displaced from the comet&#39;s path.

The radiation pressure applied by an electromagnetic wave on a perfectly absorbing surface equals the energy density of the wave. The wave&#39;s momentum ...

Education

JoVE Core

Physics

Unit 1

Electromagnetic Waves

KEY TERMS AND CONCEPTS

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

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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...

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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 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

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standing waves in a cavity

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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

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PS.7

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9-12.PS.2.2.e

9-12.P.3.7.c

Florida Department of Education

SC.912.P.10

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

South Carolina College and Career Ready Science Standards

P-PS4-4

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Radiation Pressure in Light and Space

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