# Question on geometrical optics

• Sanosuke Sagara
In summary, the conversation is about a question and solution being attached in a zip file. The person expressing their doubt mentions that it would be easier to use Paint and a text editor instead of the strange zipped xls file.

#### Sanosuke Sagara

I have my question,doubt and solution in the attachment that followed.Thanks for anybody that spend some time on this question.Sorry to say that the file format is *.zip .

#### Attachments

• optics question.zip
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Sanosuke Sagara said:
I have my question,doubt and solution in the attachment that followed.Thanks for anybody that spend some time on this question.Sorry to say that the file format is *.zip .

The object distance of a real object from a lens is always positive.

By the way, is not it easier for you to draw in Paint, for example, and write in a text editor? this zipped xls file is a bit strange.

ehild

Hello,

Thank you for sharing your question on geometrical optics. I have reviewed the attachment and have a few comments and suggestions for your solution.

Firstly, your doubt about the radius of curvature of a concave mirror is valid. It is true that the radius of curvature is always positive for a concave mirror, regardless of the sign convention. This is because the center of curvature lies on the convex side of the mirror, and the radius is measured from the center of curvature to the vertex of the mirror. Therefore, it will always be a positive value.

Secondly, your solution for finding the focal length of a concave mirror is correct. However, I would suggest including a diagram to illustrate the ray tracing method. This will make it easier for readers to understand the concept and follow your solution.

Lastly, I noticed that in your solution, you have used the sign convention where distances to the left of the mirror are positive and distances to the right are negative. While this is a valid convention, it is more commonly used to take distances to the right as positive and distances to the left as negative. I would recommend using this convention to avoid confusion.

Overall, your solution is well-explained and correct. I hope my comments and suggestions are helpful to you. Keep up the good work in studying geometrical optics!

Best regards,

## 1. What is geometrical optics?

Geometrical optics is a branch of physics that studies the behavior of light as it travels through transparent media, such as lenses and mirrors. It focuses on the laws of reflection and refraction, which determine how light rays interact with different surfaces.

## 2. What is the difference between geometrical optics and physical optics?

The main difference between geometrical optics and physical optics is the level of detail in their explanations of light behavior. Geometrical optics uses simple ray diagrams and mathematical equations to describe light as a straight line, while physical optics takes into account the wave nature of light and uses more complex mathematical models.

## 3. How is the speed of light related to geometrical optics?

Geometrical optics assumes that light travels in a straight line at a constant speed in a uniform medium. This speed is known as the speed of light, which is approximately 299,792,458 meters per second in a vacuum. The speed of light also changes when it travels through different materials, causing refraction.

## 4. Why is geometrical optics important?

Geometrical optics is important because it provides a simplified understanding of how light interacts with objects, which is crucial in fields such as optics, photography, and astronomy. It also helps in designing and understanding the behavior of optical instruments, such as microscopes and telescopes.

## 5. What are some real-life applications of geometrical optics?

Geometrical optics has numerous real-life applications, including the design of lenses and mirrors for cameras, eyeglasses, and telescopes. It is also used in the field of fiber optics, which is essential for telecommunication systems. Additionally, geometrical optics plays a significant role in the study of vision and the human eye.