When a beam of light hits a pane of glass with parallel light, the light inside gets bent. As noted on the web page, different colors of the rainbow may be bent by different angles. However, since the beam is bent on its exit by exactly the same amount as it is bent on entering, only in the opposite direction, all its parts emerge again moving in the same direction as before. Therefore, it was reasoned, a flat pane of glass does not split light into colors the way a prism does.
All the above is true. However, if you look through very thick glass, you will see fringes of rainbow

Question

When a beam of light hits a pane of glass with parallel light, the light inside gets bent. As noted on the web page, different colors of the rainbow may be bent by different angles. However, since the beam is bent on its exit by exactly the same amount as it is bent on entering, only in the opposite direction, all its parts emerge again moving in the same direction as before. Therefore, it was reasoned, a flat pane of glass does not split light into colors the way a prism does. 
All the above is true. However, if you look through very thick glass, you will see fringes of rainbow

anonymous · Answer

**color at the edges of bright objects. Why?

anonymous · Answer

ah! nice observation.......................thick glass resembles more like a prism than a flat plane of glass................isn't it?

anonymous · Answer

A thick glass has more capacity to refract the white light, so they split the light into 7 different colours. I hope it's right..