Question

At night it is difficult to see the outside objects from a well illuminated room through glass window ,but it becomes more clear if lights are switched off.Explain.

Answer 1

The glass window both reflects and refract the light but the extent of light that has to be reflected and refracted depends on the difference of light inside and outside the room. At day time, the light is refracted more both from outside and inside and reflected back just a little.
At night there is no refraction of light while the whole sum of light is reflected back from inside. that is why we can not see outside at night due to reflection of light 

Answer 2

Explanation:

It is because at night there is no light outside and inside the room,if we switch it reflection will fall outside the window and person from outside an see inside and if we switch off light ,light from outside fall and we can see from inside .