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  1. Naked Science Forum
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  4. Does light have a weight?
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Does light have a weight?

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Offline TommyJ

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Re: Does light have a weight?
« Reply #100 on: 05/08/2021 19:32:02 »
1. Electromagnetic waves consist of discrete, massless units called photons. A photon travels in vacuum at the speed of light.
2. Each photon has energy where is the frequency of the wave and h is a universal constant called Planck’s constant. The value of Planck’s constant is In other words, the electromagnetic waves come in discrete “chunks” of energy.
3. The superposition of a sufficiently large number of photons has the characteristics of a continuous electromagnetic wave.

Photon energy is E=h*f=p*c (where p - is momentum).
Can be derived from E=m*c^2 (photon m=0). In the same time m=m0*y (m0 - rest mass).
In another direction.
y*m0=(E/c^2)*c=E/c
Photon energy E=p*c.=h*f
Hence, photon momentum. p=h*f/c

The "weight"of light is a form of energy and not pounds or kilograms.
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Offline Kryptid

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Re: Does light have a weight?
« Reply #101 on: 05/08/2021 20:41:14 »
Quote from: TommyJ on 05/08/2021 19:32:02
The "weight"of light is a form of energy and not pounds or kilograms.

You could weigh it that way if you wanted to, though. If you had a container that was perfectly reflective on the inside and filled it with light, it would weigh more than if the container was empty. That's due to E=mc2.
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Offline TommyJ

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Re: Does light have a weight?
« Reply #102 on: 06/08/2021 11:16:37 »
Quote from: Kryptid on 05/08/2021 20:41:14
You could weigh it that way if you wanted to, though. If you had a container that was perfectly reflective on the inside and filled it with light, it would weigh more than if the container was empty. That's due to E=mc2.
What would be the measurement way and value as an instance?
I'd just like to mislead with confusions further.
Thank you.
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Offline Kryptid

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Re: Does light have a weight?
« Reply #103 on: 06/08/2021 17:10:06 »
Quote from: TommyJ on 06/08/2021 11:16:37
What would be the measurement way and value as an instance?

Putting it on a (sufficiently sensitive) scale would be enough. The weight would depend on how much energy the light has.
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Offline TommyJ

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Re: Does light have a weight?
« Reply #104 on: 09/08/2021 08:46:58 »
Quote from: Kryptid on 06/08/2021 17:10:06
Putting it on a (sufficiently sensitive) scale would be enough. The weight would depend on how much energy the light has.
It could be possible to direct enough directed flux a sufficiently sensitive scale, right.
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