# I Normal incidence of EM wave - p & s polarization convention?

#### IcedCoffee

Hi. I'm reading a paper "Transmission of light through a single rectangular hole in a real metal" and the author refers to the incident light shown below as "p-polarized" without further specification.

Note that ax > ay. Is there any convention in regarding a certain polarization as p-polarized in the case of normal incidence?

#### Attachments

• 13.1 KB Views: 238
Related Other Physics Topics News on Phys.org

#### Cutter Ketch

Hmmm ... that is strange. I’ve never seen anybody use S and P to mean anything other than the relation of the electric field to the plane of incidence. They shouldn’t be defined at normal incidence.

Also, since they have a well established meaning used a million places I don’t really believe we can excuse using them some other way.

However, playing devil’s advocate, S and P come from the German words for perpendicular and parallel, so I suppose if there is something to be parallel or perpendicular to other than the plane of incidence one might use that labeling. I’d be particularly accepting of that from a German speaker.

On the other hand your diagram has the electric field perpendicular to the long axis of the rectangle and still calls it P polarized, so they get no linguistic benefit of the doubt from me. This just appears to be wrong.

#### IcedCoffee

Hmmm ... that is strange. I’ve never seen anybody use S and P to mean anything other than the relation of the electric field to the plane of incidence. They shouldn’t be defined at normal incidence.

Also, since they have a well established meaning used a million places I don’t really believe we can excuse using them some other way.

However, playing devil’s advocate, S and P come from the German words for perpendicular and parallel, so I suppose if there is something to be parallel or perpendicular to other than the plane of incidence one might use that labeling. I’d be particularly accepting of that from a German speaker.

On the other hand your diagram has the electric field perpendicular to the long axis of the rectangle and still calls it P polarized, so they get no linguistic benefit of the doubt from me. This just appears to be wrong.
I guess they just picked the notation rather randomly and then expected readers to figure it out from the... figure.

Also, I think what you said would make more sense, that the direction perpendicular to the slit, or whatever structure that has some sort of axis, should be called s-polarized. Thank you!

"Normal incidence of EM wave - p & s polarization convention?"

### Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving