2 questions about em waves

[Thierry12]

1. Since skin depth is the attenuation of the wave in a conductor, this means the reflection isen't the incident wave... so what is the reflection?

2. Water doesn't stop light since it's frequency is too high, i saw on forum it's because the big ions can't move fast enought. How can that be? Wont they move as the same frequency as the wave?

Ty

 

[Bob_for_short]

1. Since skin depth is the attenuation of the wave in a conductor, this means the reflection isen't the incident wave... so what is the reflection?

2. Water doesn't stop light since it's frequency is too high, i saw on forum it's because the big ions can't move fast enought. How can that be? Wont they move as the same frequency as the wave?

Ty

The incident wave penetrates deeper than the skin layer. It makes the electrons oscillate and radiate in all directions. The waves radiated in the incident wave direction add with the incident wave. The thicker layer, the more intense the radiated wave. It happens it has the opposite sign amplitude. So the radiated and incident waves gradually cancel when you go inside.

The waves radiated with the electrons in the opposite direction are called the "reflected" waves.

In water there too few free electrons to radiate under the incident wave influence. Yet the same phenomenon takes place, so you have reflection from the water volume too.

Bob.

 

[Thierry12]

thanks alot!

 

[Thierry12]

Can someone tell me why waves arent comming out of every borders since it radiates in all directions?

 

[Born2bwire]

The total wave does not radiate in every direction though. You can decompose any wave into being the result of a summation of point sources. These point sources radiate in all directions using a spherical wave. But the sum total of all these sources is not guaranteed to radiate isotropically.

Either way though, for the most part there is generally some reflection of waves off of all surfaces.

 

[Thierry12]

thanks a lot for the help again!