# Photon question

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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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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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#4

(Original post by

How do photons not have their own intensities? I thought they were packets out energy and thus had the properties of waves 🙂

**Freedom physics**)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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#6

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So don't photons have their own amplitudes?

**Freedom physics**)So don't photons have their own amplitudes?

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#8

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Photons have their own frequencies 🙂

**Freedom physics**)Photons have their own frequencies 🙂

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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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#10

(Original post by

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 😄

**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 😄

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#12

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How does that mean photons don't have amplitude? 🙂

**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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#13

**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 😄

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#16

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.

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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Thanks! Can you also explain: intensity is directly proportional to amplitude squared with that? 😄 🙂

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#18

(Original post by

Thanks! Can you also explain: intensity is directly proportional to amplitude squared with that? 😄 🙂

**Freedom physics**)Thanks! Can you also explain: intensity is directly proportional to amplitude squared with that? 😄 🙂

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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#19

(Original post by

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!

**-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!

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*v

^{2}to wave intensity. Salute!

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