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logical
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One of my project will work with a great success if the light can exert force.
Can it be possible?
Can it be possible?
logical said:One of my project will work with a great success if the light can exert force.
Can it be possible?
ZapperZ said:Light (as in photons) carries momentum. Any change in that momentum (such as absorption or reflection), will impart a force. So yes, it can exert a force. There's a simple experimental demonstration which has a set of 4 paddles being painted black on one side of each paddle, and while on the other, that spins simply when you shine light on it.
However, if your "great success" depends on using this to "move" objects substantially, you might be disappointed.
Zz.
greeniguana00 said:I think what you are talking about is called a radiometer. What causes it to spin is not the change in momentum from light "particles" hitting the paddles. In fact, the black side of the paddles absorbs much of the incoming light, causing the black side to heat up, while the white side stays cool because it reflects the light. When air molecules inside the radiometer hit the black side, kinetic energy is imparted to them, and the change in momentum of the air molecules (away from the black side) means an equal and opposite change in momentum happens to the paddle. Because there is a partial vacuum in the radiometer, these air molecules mostly flow freely until they hit either a paddle or the side of the radiometer, and it is more likely for them to hit the glass surface and slow down before hitting the white side of the paddle (which would cause turning in the opposite direction).
logical said:One of my project will work with a great success if the light can exert force.
Can it be possible?
dst said:Unless your project involves space and several square kilometres of material, don't count on getting any useful work done.
pam said:If light is reflected from a metal surface, it exerts a pressure (in dynes/cm^2) given by
p=2I/c, where I is the intensity in ergs/(cm^2-sec) and c is the speed of light.
As dst said, I don't think you can measure this small pressure in the laboratory,
although it is a possible option for space travel ("solar sailing").
Go here and scroll down to "physical properties":cdotter said:When we feel forces in the real world, we feel electrostatic repulsions, right? But photons don't have a charge (I think?), so how can they exert a force?
Yes, light can exert a force on objects. This force is known as radiation pressure or solar pressure, and it is caused by the transfer of momentum from photons, which are particles of light, to the surface of an object they strike.
Light can exert force on objects through the transfer of momentum from photons. When light strikes the surface of an object, the photons collide with the particles on the surface, transferring their momentum and causing the object to experience a force in the direction of the incoming light.
Light can exert force on any object that it strikes, regardless of its size or composition. However, the amount of force exerted will vary depending on the properties of the object, such as its reflectivity and surface area.
In most cases, the force exerted by light is very small and difficult to detect. However, in certain situations, such as when an object is exposed to intense laser light, the force can be strong enough to have noticeable effects.
Yes, light can exert a force in a vacuum. In fact, the lack of air resistance in a vacuum can actually allow light to exert a stronger force on an object, as there is nothing to slow down or deflect the photons as they collide with the object's surface.