travelingkitkat
New member
Please help... I'm stumped.
Question:
Shown from above in the figure is one corner of a rectangular box filled with water. A laser beam starts 10 cm from side A of the container and enters the water at position . You can ignore the thin walls of the container.
Picture:
http://session.masteringphysics.com/problemAsset/1074297/3/knight_Figure_23_50.jpg
a)If x=15cm, does the laser beam refract back into the air through side B or reflect from side B back into the water?
It reflects... it was multiple choice, so I just guessed. Could you explain why? I think it has to do with the n values (n water = 1.33 limiting the ability of it to go back into air because the angle is bigger than 90* when sintheta2 multiplied by 1.33) but I'm not sure how to calculate that.
b)If x=15cm, does the laser beam refract back into the air through side B or reflect from side B back into the water? Determine the angle of refraction or reflection.
I got this one and it was 51.3*. I used arctan (15/10) to get theta one=56.3*
Then I did n1sintheta1=n2sintheta2 to get theta2 (angle of refraction in water) which = 38.7*
Subtracted that from 90* to get the angle of reflection = 50.3*
c) Repeat part B for x=25cm.
Tried doing what I did for B, didn't work. Tried making it refract, also didn't work. Totally lost.
d)Find the minimum value of x for which the laser beam passes through side B and emerges into the air.
Again, I have no idea. If I understood A, I could probably do this.
Also, for clarification when it asks for the angle of reflection or refraction is that always 90-theta2? I guess I don't really understand that terminology. I thought it was theta2 based on how it was explained in class but I've been getting the wrong answer originally for a bunch of those (and then it ends up being 90-theta2).
Thanks!
Question:
Shown from above in the figure is one corner of a rectangular box filled with water. A laser beam starts 10 cm from side A of the container and enters the water at position . You can ignore the thin walls of the container.
Picture:
http://session.masteringphysics.com/problemAsset/1074297/3/knight_Figure_23_50.jpg
a)If x=15cm, does the laser beam refract back into the air through side B or reflect from side B back into the water?
It reflects... it was multiple choice, so I just guessed. Could you explain why? I think it has to do with the n values (n water = 1.33 limiting the ability of it to go back into air because the angle is bigger than 90* when sintheta2 multiplied by 1.33) but I'm not sure how to calculate that.
b)If x=15cm, does the laser beam refract back into the air through side B or reflect from side B back into the water? Determine the angle of refraction or reflection.
I got this one and it was 51.3*. I used arctan (15/10) to get theta one=56.3*
Then I did n1sintheta1=n2sintheta2 to get theta2 (angle of refraction in water) which = 38.7*
Subtracted that from 90* to get the angle of reflection = 50.3*
c) Repeat part B for x=25cm.
Tried doing what I did for B, didn't work. Tried making it refract, also didn't work. Totally lost.
d)Find the minimum value of x for which the laser beam passes through side B and emerges into the air.
Again, I have no idea. If I understood A, I could probably do this.
Also, for clarification when it asks for the angle of reflection or refraction is that always 90-theta2? I guess I don't really understand that terminology. I thought it was theta2 based on how it was explained in class but I've been getting the wrong answer originally for a bunch of those (and then it ends up being 90-theta2).
Thanks!