Is the Amplitude Coefficient of Reflection Always 0 at 90 Degrees?

[alchemist7]

At what angle of incidence is amplitude coefficient of reflection parallel to the incidence plane 0?

my solution is that by Fresnell's equation, r//=tan(i-i`)/tan(i+i`)=0, i=i`,i=90.so for whatever surface,angle of incidence should be 90.

is it correct? different from the answer!

 

[LowlyPion]

Is what you're trying to find the Brewster's angle by any chance?

http://en.wikipedia.org/wiki/Brewster's_angle

 

[nlightner]

Your solution is partially correct. The amplitude coefficient of reflection being parallel to the incidence plane does indeed occur at an angle of incidence of 90 degrees, also known as the normal angle. However, it is not always the case that the amplitude coefficient of reflection will be 0 at this angle. This only occurs for surfaces with a perfectly smooth and flat interface, known as a specular reflection. In most cases, there will still be some reflection at this angle, but it will be significantly reduced compared to other angles of incidence.