Why can't light pass through to the dark side of a window?

[danHa]

if I would look through a window on darker area I would see my reflection instead of the outside world . but if the other side of the window is light then the light may pass through the window does the light outside effect the window and make the refraction disappear ?.
or the light always cross both window side but our eye filter the reflection when more light is coming outside ?.
what happens if I point laser from two side of the window in difference angles on the same point would only one laser come trough the window ?.

 

[A.T.]

or the light always cross both window side but our eye filter the reflection when more light is coming outside ?.

Yes. The eye adapts to the total amount of light coming in, so you see the reflection better if there is less light coming trough the window.

 

[Ibix]

The reflected and transmitted images are always there. Your eye picks up the brighter image and ignores the dimmer one - it may not even be able to detect the dimmer image if the brighter one is too bright.

Sometimes the brightnesses of the two images are comparable and you can see both. You can probably see this if you live in a built up area - turn on a light inside after dark and look out at the street. You'll probably be able to see both your reflection and the outside world.

A rule of thumb (from 20 year old memory, so beware!) is that about 4% of light is reflected at each glass/air boundary. So your side needs to be quite a lot brighter than the other side for you to see a reflection.

 

[Keith_McClary]

"One-way mirror"

 

[Redbelly98]

A rule of thumb (from 20 year old memory, so beware!) is that about 4% of light is reflected at each glass/air boundary.

Correct. Generally 3.5% to 4%, depending on the specific type of glass.

The formula is $\left( \frac{n-1}{n+1} \right) ^2$.

 

[danHa]

Yes. The eye adapts to the total amount of light coming in, so you see the reflection better if there is less light coming trough the window.

Correct. Generally 3.5% to 4%, depending on the specific type of glass.

The formula is $\left( \frac{n-1}{n+1} \right) ^2$.

what n stand for?

 

[Motore]

what n stand for?

https://en.wikipedia.org/wiki/Refractive_index