Photons and refraction

[inaccensa]

EK says that reflection can be explained by the wave theory of light. The photons collide with the interface of a medium and reflect. Thus conserving KE and momentum. Can someone plz explain what happens with refraction? Since the speed ( assuming that it moves from air to water) decreases, the KE must decrease. What I don't understand is that if the same light were to pass through water and emerge back into air, it will have the same speed with which it entered water, since the angles are same.

Air-----
Water------
Air------

---

Members don't see this ad.

 

[Omni]

Here's what my explanation to it is:
Don't look at it in terms of energy.
look at it as V=λf
f will always stay the same, but λ and V will change to compensate for it.

And KE isn't conserved, so you can't look at it in terms of energy. The initial isn't going to equal the final with non-conserved systems.

 

[inaccensa]

Here's what my explanation to it is:
Don't look at it in terms of energy.
look at it as V=λf
f will always stay the same, but λ and V will change to compensate for it.

And KE isn't conserved, so you can't look at it in terms of energy. The initial isn't going to equal the final with non-conserved systems.

i thought the energy was conserved.

 

[zmatrix]

KE (= 1/2 mv^2) is useless for massless objects, like the photon.

It seems like you think that since the photon is traveling slower in another medium that it has less energy (kinetic energy). That is not the case since E = hf and the frequency is unchanged in the slower medium.

Light slows down in glass because it is "interacting" with with the matter within, but at no time does it lose energy.

 

[premed101]

EK says that reflection can be explained by the wave theory of light. The photons collide with the interface of a medium and reflect. Thus conserving KE and momentum. Can someone plz explain what happens with refraction? Since the speed ( assuming that it moves from air to water) decreases, the KE must decrease. What I don't understand is that if the same light were to pass through water and emerge back into air, it will have the same speed with which it entered water, since the angles are same.

Air-----
Water------
Air------

Isn't reflection the particle theory of light?
Diffraction and interference were the ones I believe that need the wave theory

 

[Isoprop]

Isn't reflection the particle theory of light?
Diffraction and interference were the ones I believe that need the wave theory

Sort of. You can use either wave or particle theory to explain any of light's behavior. As long it fits, you would be right. Only the wave theory of light explains why light reflects at a 180 degree phase difference. But the particle theory makes it clear why the incident angle and angle of reflection are equal.