How Thick Is the Glass Plate Based on Visibility Circle?

  • Thread starter Thread starter ERB225
  • Start date Start date
  • Tags Tags
    Optics
AI Thread Summary
The discussion revolves around determining the thickness of a glass plate based on visibility through it, with a critical angle of 41.8º and a refractive index of 1.5. The original question is deemed poorly formulated, as it lacks clarity on the distance of the observer from the glass. It is noted that the observer would need to be in contact with the glass for total internal reflection to limit visibility to a 1-meter radius. After interpretation, it is concluded that the glass plate would need to be 381 inches thick for the specified visibility conditions. The wavelengths mentioned are considered irrelevant to the solution.
ERB225
Messages
1
Reaction score
0
Optics question-- please reply ASAP

A person stands against a thick plate of glass, n=1.5. everything on the other side of the glass plate is inside of a circle of radius = 1 meter.
wavelength air = 600 x 10 ^ -9 meters
wavelength of glass = 4 x 10 ^ -7 meters
Critical angle of glass plate = 41.8º

HOW THICK IS THE GLASS PLATE?
 
Last edited:
Physics news on Phys.org
This problem is pooly formulated and posted.

Glass doesn't have a wavelength, and how far is the person from the glass?

If my eyeball doesn't touch the glass then I will see all the way to infinity, not
just to a 1 meter radius. My eyeball would have to be in fluid contact with the
window in order for there to be a point of total internal reflection which is visible
to me.

That having been said, the glass plate would be 381 Inches thick.
 
I agree that the problem is not clearly stated. I interpret it this way: looking at the person's image from the other side of the glass, every point is only visible inside a circle of radius 1 meter. With this interpretation, the problem is solvable. (The wavelengths are irrelevant.)
 
Thread 'Variable mass system : water sprayed into a moving container'
Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
Back
Top