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
WEll, you have the angles of incidence of 48.2, so use snell's law to get the angle of refracation.
To determine the Brewster angle, we need to calculate the angle of incidence at which the reflected light is completely polarized parallel to the interface between the ethanol and crown glass.
The formula for the Brewster angle (angle B) is given by:
tan(B) = nR/ni
where nR is the refractive index of the crown glass and ni is the refractive index of ethanol.
In this case, nR = 1.52 (for crown glass) and ni = 1.36 (for ethanol).
So, tan(B) = 1.52/1.36 = 1.12
To find B, take the arctan of 1.12. Using a calculator, this gives us B = 48.2 degrees.
Now, let's illustrate this with a light ray diagram.
1. Draw a horizontal line to represent the interface between ethanol and crown glass.
2. Label the top side as "ethanol" and the bottom side as "crown glass."
3. Draw a vertical incident ray coming from the left side, hitting the interface at an angle of 48.2 degrees.
4. At the interface, draw a normal line perpendicular to the interface.
5. Draw the refracted ray at a different angle according to the laws of refraction. The exact angle depends on the incident angle and the refractive indices.
6. Draw a reflected ray coming from the interface at an angle equal to the incident angle.
The significance of the Brewster angle is that when light is incident at this angle, the reflected light is fully polarized parallel to the interface. This means that the reflected light consists only of electric field vibrations in one direction, which can be useful in applications such as glare reduction or polarization filters.