Index of when refraction/optics question

In summary, the conversation discusses using a microscope to focus on a black dot and how placing a piece of plastic over the dot affects the focus. The question asks for the index of refraction of the plastic, and the relevant equations and ideas include Snell's law and real and apparent depth. It is suggested to use triangles to figure out the angles needed for the calculation and to start with a diagram.
  • #1
Gino97
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0
The question
A microscope is focused on a black dot. When a 1.20 cm -thick piece of plastic is placed over the dot, the microscope objective has to be raised 0.380 cm to bring the dot back into focus.

What is the index of refraction of the plastic

Relevant equations/ideas
n1*sin(theta1)=n2*sin(theta2)

Trying to solve
I know I must use triangles to figure out the angles needed for Snells law, but have more unknown variables than equations to relate them so I don't know how to solve for them
 
Last edited:
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  • #2
Have you come across real and apparent depth? For example, when you look into a pool of water, it appears shallower than it really is, due to refraction.

Also, you could pick an arbitrary angle and do the calculation for that. Edit: And I'd always start with a diagram (or several.)
 

1. What is an index of refraction?

The index of refraction is a measure of how much a material can bend or refract light. It is defined as the ratio of the speed of light in a vacuum to the speed of light in a given material.

2. How is the index of refraction calculated?

The index of refraction is calculated by dividing the speed of light in a vacuum by the speed of light in the material. This can be represented by the equation n=c/v, where n is the index of refraction, c is the speed of light in a vacuum (3 x 10^8 m/s), and v is the speed of light in the material.

3. What factors affect the index of refraction?

The index of refraction can be affected by various factors, including the density and composition of the material, as well as the wavelength of light passing through it. The index of refraction also tends to increase with increasing temperature.

4. How does the index of refraction relate to the angle of refraction?

The index of refraction directly affects the angle of refraction, which is the angle at which light bends as it passes from one material to another. The higher the index of refraction, the more the light will bend, resulting in a larger angle of refraction.

5. How does the index of refraction impact optical devices?

The index of refraction plays a crucial role in the functioning of optical devices such as lenses, prisms, and mirrors. These devices use the principles of refraction to manipulate and focus light, and the index of refraction of the materials they are made of determines how effectively they can do so.

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