Homework Help: Physics

Posted by Katie on Sunday, May 31, 2009 at 4:01pm.

I don't understand snell's law ( nsin(0)=nsin(0) ) and how to use it with refraction.

also how do i apply that to this problem:
'a light ray enters a square piece of plastci (n=1.39) near a corner. as it encounters the adjacent side it gets refracted along the surface (it hits at the critical angle). what was the original angle with which the ray hit the plastic from air?'
i know the answer (75 degrees) but i don't know how to get there.
please help!

Physics - bobpursley, Sunday, May 31, 2009 at 4:15pm
What does "near a corner" mean? Does that mean the ray is internally reflected once?
Physics - Katie, Sunday, May 31, 2009 at 4:24pm
i have no idea, i just wrote what the question said. but yes thats what i interpreted it to mean
Physics - bobpursley, Sunday, May 31, 2009 at 4:40pm
Then start at the end of the ray.

1.39*sinThetainside=1*sin90
theta inside =46 deg.
Now take that angle back to where it was reflected, so it incident angle at the reflection was 46, then trace back to the corner side, so it leaves the surface refracted at 54 deg, no use Snell's law to find the ray angle outside ..

1.39sin54=1*sinTheta
and I think you will get your 75deg. Draw the figure to make certain you understand it.
- Physics - bobpursley, Sunday, May 31, 2009 at 4:41pm
  oops, typo it is 44 deg, not 54 deg. The sum has to be 90 between 46 and 44.

Answer this Question

Related Questions

Physics - The maximum depth of Lake Baikal, in Russia, is 1637 m, making it the ...
Physics Word Problem - using Snell's Law (sin(theta1)/sin(theta2) = v1/v2 ...
Physics Word Problem - using Snell's Law (sin(theta1)/sin(theta2) = v1/v2 ...
math - Snell's law of refraction can be written as sin i = n sin r, where n ...
CALCULUS - For the sequence below, determine whether they converge or not, and ...
physics - light travels from ethanol intro crown glass. what's the brewster ...
math - Snell's law of refraction can be written as sin i = n sin r, where n ...
Physics - Find the angle of refraction if there is one. If there isn't, tell...
Physics - A ray of light of frequency 5.09 x 10^14 Hz passes from air into flint...
Physics - A ray of light stikes a flat 2 cm thick block of ice (n=1.5) at an ...

For Further Reading

First Name:
School Subject:
Answer: