# physics

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light travels from ethanol intro crown glass. what's the brewster angle in this situation? illustrate your answer with a light ray diagram. what's the signifcance of this angle of incidence?

n1=1.36for ethanol
nR=1.52 for crown glass

tanangleB=nR/ni
=1.52/1.36
=1.12 (48.2 degrees)

the only thing that I have in the diagram is the face that both the incident and reflected rays are 48.2 degrees in the ethanol..not even sure if that is right.

not sure how to draw it or what the signicance is....please explain.

physics - bobpursley, Saturday, January 16, 2010 at 3:44pm

Bob - I looked at the website you gave me. In order to draw it, do I need to also figure out the angle of incidence and reflection? If so, how do i do that...thanks

physics - bobpursley, Saturday, January 16, 2010 at 5:25pm
WEll, you have the angles of incidence of 48.2, so use snell's law to get the angle of refracation.

okay so I did that, and have my diagram drawn now, but what is the significance? I know that the angle of incicdence, from Brewster'slaw, is 48.2 degrees, and the angle of refraction, from Snell' Law, is 41.84. However this wouldn't be total internal reflection, since its going from ethanol -->crown glass, which is lower index of refraction to higher and total internal reflection requires from higher to lower. So why is significant about this then?

• physics - ,

The Brewster angle and the Total Internal Reflection angles are different. When light is incident at the Brewster angle, the refracted wave and reflected waves are perpendicular.

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

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