# How double glasses window reflect ?

• vkash
In summary, the conversation discusses the reflection seen on the glass windows of trains when they are underground or have a wall behind them. The person who starts the conversation shares their observations and theories about the reflection, mentioning that they have read about optics but still cannot fully explain it. They also mention that the windows are double glass, which they believe is to prevent the train from getting too hot in the summer. Another person responds with their explanation, saying that the amount of light coming from outside affects the intensity of the reflected light seen from inside the train. They also suggest looking into the Fresnel equations for further understanding. The original person thanks both respondents and confirms that their explanation is correct.
vkash
Today when i was traveling in train(from my study center to home) i found a common but unexplained thing that is a little reflection can be seen on Glass window of train when it is underground or there is any wall behind the windows BUT when there is no window(ex when it is in station there is a lot of light) then i can't see any kind of reflection in window (or very very little reflection). I had read very little on Optics like Lens maker formula etc. I try to explain this during my 30 minute journey but i can't so i want to know it's answer from you why there is reflection in glass window.why this glass window was reflecting when it was underground. This glass window was double(one plate of glass after other as i see) i think because they(manufacturer of train) do this to don't make it hot due to sun in summer/ keep train cool with it's AC.One thing i also want to say that there a lot of lights inside train as a source of light for reflection.

How I explain it.
first explanation::-> This reflection happen due to reflection backward wall. Limitation wall did not reflect.
second explanation ::-> Double glass window of train reflect light rays every time but i can see them only at that time when there is any obstacle that does not overcome the intensity of light of reflected rays by glass window in case of stations there is light entering inside train which overcome the intensity of reflected light by glass window but when it is underground no light enter externally so i can see reflection of persons inside train. this idea has recently came in mind is it correct? Or there is any other explanation for this?

there is no double glass window in my house or nearby to experiment so you tell me.

Last edited:
vkash said:
Today when i was traveling in train(from my study center to home) i found a common but unexplained thing that is a little reflection can be seen on Glass window of train when it is underground or there is any wall behind the windows BUT when there is no window(ex when it is in station there is a lot of light) then i can't see any kind of reflection in window (or very very little reflection). I had read very little on Optics like Lens maker formula etc. I try to explain this during my 30 minute journey but i can't so i want to know it's answer from you why there is reflection in glass window.why this glass window was reflecting when it was underground. This glass window was double(one plate of glass after other as i see) i think because they(manufacturer of train) do this to don't make it hot due to sun in summer/ keep train cool with it's AC.One thing i also want to say that there a lot of lights inside train as a source of light for reflection.

How I explain it.
first explanation::-> This reflection happen due to reflection backward wall. Limitation wall did not reflect.
second explanation ::-> Double glass window of train reflect light rays every time but i can see them only at that time when there is any obstacle that does not overcome the intensity of light of reflected rays by glass window in case of stations there is light entering inside train which overcome the intensity of reflected light by glass window but when it is underground no light enter externally so i can see reflection of persons inside train. this idea has recently came in mind is it correct? Or there is any other explanation for this?

there is no double glass window in my house or nearby to experiment so you tell me.
It looks like you have the right idea. Glass will always reflect part of the light that strikes it and will always transmit some of that incident light.

If there is no light coming from outside the train, the only light you will see from the window will be light from inside reflected back to you. If there is a lot of light outside, the light coming from the window will consist mostly of outside light transmitted through the window with a relatively small amount of light reflected back from the inside, so the reflected light will be hard to distinguish.

AM

Andrew Mason said:
It looks like you have the right idea. Glass will always reflect part of the light that strikes it and will always transmit some of that incident light.

If there is no light coming from outside the train, the only light you will see from the window will be light from inside reflected back to you. If there is a lot of light outside, the light coming from the window will consist mostly of outside light transmitted through the window with a relatively small amount of light reflected back from the inside, so the reflected light will be hard to distinguish.

AM

Thanks Andrew.

I was excepting that there will many replies for this question but Here is only 1.:zzz:
I need more replies to confirm it 100% so please post your opinion guys!.

## 1. How do double glazed windows reflect heat and light?

Double glazed windows have two panes of glass with a layer of air or gas in between. This layer acts as an insulator, preventing heat from transferring between the inside and outside of the window. The glass also has a low-emissivity coating which reflects heat and light back into the room, keeping it warmer in the winter and cooler in the summer.

## 2. What is the difference between single and double glazed windows in terms of reflection?

Single glazed windows only have one pane of glass, so they do not have the insulating layer or the low-emissivity coating that double glazed windows have. This means that single glazed windows do not reflect heat and light as effectively as double glazed windows.

## 3. How does the angle of the double glazed window affect its reflection?

The angle of the window does not affect its ability to reflect heat and light, but it can affect the amount of light and heat that enters the room. For example, a window facing the sun at a steep angle will allow more heat to enter the room compared to a window facing the sun at a lower angle.

## 4. Do all double glazed windows have the same reflective properties?

No, the reflective properties of double glazed windows can vary depending on the type of glass and coating used. Some may have a higher reflectivity, while others may have a lower reflectivity. It is important to research and choose the right type of double glazed window for your specific needs.

## 5. Can double glazed windows reduce outside noise?

While the primary purpose of double glazed windows is to insulate against heat and light, they can also help reduce outside noise due to the thickness of the glass and the insulating layer. However, the amount of noise reduction will depend on the type of glass and the thickness of the window, so it is important to consider these factors when choosing double glazed windows for noise reduction purposes.

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