How Does Glass Thickness Affect Refractive Index Calculation?

So, the angle between the ray and the normal at the point where the ray hits the back surface is the same as the angle between the reflected ray and the normal at the point where it hits the back surface. In summary, when a bright point source is focused on a glass plate with a lightsensitive emulsion, the developed photograph will show a halo around the image of the spot. The glass plate in this scenario is 3.10 mm thick and the halos have an inner radius of 5.34 mm. The index of refraction of the glass can be determined to be approximately 1.532, with the assumption that the reflected ray is tangent to the upper end of the halo and reflects halfway on the back surface. The
  • #1
kent davidge
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Homework Statement



Old photographic plates were made of glass with a lightsensitive emulsion on the front surface. This emulsion was somewhat transparent. When a bright point source is focused on the front of the plate, the developed photograph will show a halo around the image of the spot. If the glass plate is 3.10 mm thick and the halos have an inner radius of 5.34 mm, what is the index of refraction of the glass? (Hint: Light from the spot on the front surface is scattered in all directions by the emulsion. Some of it is then totally reflected at the back surface of the plate and returns to the front surface.)

Homework Equations



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The Attempt at a Solution


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Is my sketch for the situation correct? I found n = 1.532 and the book answer is also 1.53.
Since the reflected ray is tangent to the upper end of halo, I assumed the ray reflecting half-way in the back surface. Is it correct?

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  • #2
I think that's right.. the angle of incidence is always equal to the angle of reflection.
 

FAQ: How Does Glass Thickness Affect Refractive Index Calculation?

What is the refractive index?

The refractive index is a measure of how much light is bent, or refracted, when it passes through a medium, such as air, water, or glass.

How is the refractive index measured?

The refractive index is measured by measuring the ratio of the speed of light in a vacuum to the speed of light in the medium.

What is the relationship between the refractive index and the speed of light?

The refractive index is inversely proportional to the speed of light in a medium. This means that as the refractive index increases, the speed of light decreases.

Why is the refractive index important?

The refractive index is important because it affects how light travels through and interacts with different materials. For example, it determines the amount of bending that occurs when light passes through a lens, and it is also used in the design of optical devices such as microscopes and telescopes.

What factors can affect the refractive index?

The refractive index can be affected by several factors, including the temperature and pressure of the medium, the wavelength of the light, and the chemical composition of the material.

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