Freedom physics
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Why is the energy of a photon independent of its intensity? 😄
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Webhawk
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Intensity of a light/ E.M. radiation source relates to the number of photons per second per unit area it emitts.The energy of a photon is dictated by the electromagnetic interaction which produced it.Photons themselves do not have an intensity. Hope this helps!
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Freedom physics
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How do photons not have their own intensities? I thought they were packets out energy and thus had the properties of waves 🙂
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Sinnoh
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(Original post by Freedom physics)
How do photons not have their own intensities? I thought they were packets out energy and thus had the properties of waves 🙂
And they also have the properties of particles. The intensity is the rate of emission of photons from a source, so a photon by itself doesn't have intensity in the same way that a single electron doesn't.
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Freedom physics
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So don't photons have their own amplitudes?
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Presto
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(Original post by Freedom physics)
So don't photons have their own amplitudes?
Why do you think that? How can that be?
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Freedom physics
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Photons have their own frequencies 🙂
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Presto
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(Original post by Freedom physics)
Photons have their own frequencies 🙂
I know that they have their own frequencies and wavelengths but what does that have anything to do with amplitude? If they do have amplitude, how can the amplitude be represented and are there any equations/graphs related to their amplitude?
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Freedom physics
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Photons are light waves, light waves are transverse waves and they have amplitude so photons have amplitudes 🙂, I had to refer to a friend lol 😄
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username3472470
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(Original post by Freedom physics)
Photons are light waves, light waves are transverse waves and they have amplitude so photons have amplitudes 🙂, I had to refer to a friend lol 😄
You’re getting confused. A light can act as a photon which is a particle and the evidence is provided by the photoelectric effect. It can also act as a wave and the evidence of this is provided by interference of light waves.
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Freedom physics
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How does that mean photons don't have amplitude? 🙂
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username3472470
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(Original post by Freedom physics)
How does that mean photons don't have amplitude? 🙂

You need to think of a photon as a particle and treat it separately from a light wave.
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Presto
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(Original post by Freedom physics)
Photons are light waves, light waves are transverse waves and they have amplitude so photons have amplitudes 🙂, I had to refer to a friend lol 😄
A photon is a discrete packet of EM radiation but in layman's terms it's a particle that carries light so it behaves both as a particle and a wave. A photon itself isn't a light wave, it's a carrier so lots of photons make light a photon itself isn't light wave I believe
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Bulletzone
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E = hf

Do you see Intensity in the equation?

/thread
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Freedom physics
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Thank you! 😄
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-andromeda-
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OP i know your question seems to have been answered but if it helps, the way i got around this was understanding that the intensity of a photon-emitting source controls the rate of photons emitted, not their energy.

for instance, with low intensity you get less photons emitted per second. they all still have the same energy and frequency, but there are just less of them per second.
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Freedom physics
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Thanks! Can you also explain: intensity is directly proportional to amplitude squared with that? 😄 🙂
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-andromeda-
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(Original post by Freedom physics)
Thanks! Can you also explain: intensity is directly proportional to amplitude squared with that? 😄 🙂
this is a little tricky to explain without a diagram but i’ll try my best!

draw a displacement time graph for two waves. one has double the amplitude of the other. measure their gradients at the rest position and you should find the double amplitude wave has double the normal wave's gradient. since on a displacement time graph gradient equals velocity, the double amplitude wave has double velocity of the other wave.

intensity = power/area = energy/time / area.

kinetic energy = 1/2 x mass x VELOCITY SQUARED.

so intensity equals (1/2 x mass x velocity squared)/(area x time) from these equations.

as the velocity of the double amplitude wave is double, the velocity squared will be four times as big. therefore intensity will be four times as big.

intensity = 4x big, amplitude = 2x big so intensity is proportional to amplitude squared. hope this helps!
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Eimmanuel
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(Original post by -andromeda-)
this is a little tricky to explain without a diagram but i’ll try my best!

draw a displacement time graph for two waves. one has double the amplitude of the other. measure their gradients at the rest position and you should find the double amplitude wave has double the normal wave's gradient. since on a displacement time graph gradient equals velocity, the double amplitude wave has double velocity of the other wave.

intensity = power/area = energy/time / area.

kinetic energy = 1/2 x mass x VELOCITY SQUARED.

so intensity equals (1/2 x mass x velocity squared)/(area x time) from these equations.

as the velocity of the double amplitude wave is double, the velocity squared will be four times as big. therefore intensity will be four times as big.

intensity = 4x big, amplitude = 2x big so intensity is proportional to amplitude squared. hope this helps!
I really admire your bravery

IMO, your explanation "could be a flaw". I don't you are taught of waves having mass, so I don't really understand how you can apply KE = 1/2*m*v2 to wave intensity. Salute!
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