Question

Light cannot be seen through a bent pipe. why,?

Answer 1

Because the light travels in a straight line... A bent pipe does not provide a straight pathway for the light to follow chance light cannot be seen through a bent pipe

Answer 2

Due to its property called Rectilinear Propagation , light only travels in straight paths .
Thus , when there's a bent pipe , light stops where the pipe is bent and can't be seen on the other side .