# Classically, how can I explain Reflection?

• jaumzaum
In summary: Classical physics is not what we are discussing here.In summary, the frequency of oscillation of an electron in a metal is 180° shifted from the original wave, so forward waves are canceled and 100% of the wave is reflected, by conservation of energy. This is why metals are transparent to visible light, and why higher frequencies cannot be seen through them.
jaumzaum
Hello guys! I was trying to understand (without involving too much QM) how does reflection works, and why metals reflect almost 100% of visible light while glass does not, and also why when we increase the frequency, metals become transparent.

I know that when any single photon reaches a body, it interacts with all the electrons in the body, and I can explain that in classical physics considering the photon as a wave. The photon makes the electrons oscillate and create a secondary wave in all directions. In metals the frequency of oscillation of these electrons are 180° shifted from the original wave, so forward waves are canceled and 100% of the wave is reflected, by conservation of energy. In other substances, some part of the wave is reflected, some part is refracted, and some part is absorbed.

Ok, this is what I read, and I don't know if it's completely true or well-written. My question is, why metals generate a secondary wave that is 180 ° shifted from the light wave? And why, for higher frequencies, this isn't true?

davenn
Electric field is zero in metal. It means no light as EM wave in metal.

anuttarasammyak said:
Electric field is zero in metal. It means no light as EM wave in metal.

So why are metals transparent in high frequency waves?

Last edited:
jaumzaum said:
I know that when any single photon reaches a body, it interacts with all the electrons in the body
Wait a cotton pickin' second. You wanted a Classical Explanation. Photons don't come into that, however you state it. If you insist on using photons (perhaps you think it is somehow a deeper explanation) then you need to use their wave nature of their probability so you are back with waves anyway.
Little bullets may be a comforting image but light never behaves like little bullets.

vanhees71

## 1. What is reflection in classical physics?

Reflection in classical physics refers to the phenomenon of a wave or particle bouncing off a surface, changing direction but maintaining its original energy and frequency. This can be seen in the reflection of light off a mirror or sound off a wall.

## 2. How does reflection occur?

Reflection occurs when a wave or particle encounters a boundary or surface that it cannot pass through. The wave or particle then bounces off the surface, changing direction but maintaining its original properties such as energy and frequency.

## 3. What is the law of reflection?

The law of reflection states that the incident angle (the angle at which the wave or particle approaches the surface) is equal to the reflected angle (the angle at which the wave or particle bounces off the surface). This can be seen in the reflection of light off a flat mirror, where the angle of incidence is equal to the angle of reflection.

## 4. How is reflection different from refraction?

Reflection and refraction are both phenomena that occur when a wave or particle encounters a boundary or surface. The main difference is that in reflection, the wave or particle bounces off the surface and changes direction, while in refraction, the wave or particle passes through the surface and changes direction.

## 5. What are some real-life examples of reflection?

Reflection is a common occurrence in our daily lives. Some examples include the reflection of light off a mirror, the reflection of sound off a wall, and the reflection of radio waves off the ionosphere. Other examples include the reflection of water waves off a barrier and the reflection of seismic waves off different layers of the Earth's crust.

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