#1
We've been told that the energy of a photon is only dependent on wavelength, but the equation E = (hc)/λ, shows that E is dependent on c, the speed of the photon too.
I understand that h is a constant, so does not affect the energy, but I thought that the speed of the photon can vary as it enters different mediums with different refractive indices. For example, the speed of the photon decreases as it goes from air to glass. Would this not mean that the speed of the photon can also affect the photon energy?
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2 years ago
#2
(Original post by Rubberbandit)
We've been told that the energy of a photon is only dependent on wavelength, but the equation E = (hc)/λ, shows that E is dependent on c, the speed of the photon too.
I understand that h is a constant, so does not affect the energy, but I thought that the speed of the photon can vary as it enters different mediums with different refractive indices. For example, the speed of the photon decreases as it goes from air to glass. Would this not mean that the speed of the photon can also affect the photon energy?
From what I understand c is the speed of light and is a constant and therefore doesn't change as a result. The only value that affects it is wavelength as h (planck's constant is also a constant).

*Also doing as physics and trying to wrap my head around this last section *
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2 years ago
#3
My friend, photons travel only at the speed of light. So the top bit of equation is technically constant

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2 years ago
#4
C is constant, the wavelength does however change in a medium
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2 years ago
#5
(Original post by Rubberbandit)
We've been told that the energy of a photon is only dependent on wavelength, but the equation E = (hc)/λ, shows that E is dependent on c, the speed of the photon too.
I understand that h is a constant, so does not affect the energy, but I thought that the speed of the photon can vary as it enters different mediums with different refractive indices. For example, the speed of the photon decreases as it goes from air to glass. Would this not mean that the speed of the photon can also affect the photon energy?
The "speed" is always constant for a photon, it's an elementary particle that doesn't interact with the higgs field, thus the speed has to be 299,792,458 m/s, otherwise it would't be a photon anymore!

When light travels through a vacuum there's nothing to "bump" into, but if enters another medium, say, glass there's a lot of stuff to bump into, so the photon bumps around and moves through the substance in a zigzag pattern, thus to us it seems the photon slowed down, it didn't, it just had to travel a longer distance because it was bumping around. The denser the material the more stuff it'll bump into, the longer it'll take to reach the other end, but it's speed remains the same.
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