In general, when a ray of light passes through a lens, there occurs a change in its direction of propagation. Why?

In general, when a ray of light passes through a lens, there occurs a

1.	In general, when a ray of light passes through a lens, there occurs a change in its direction of propagation. Why?
Answer» The working of a lens is similar to that of a triangular prism. When a ray of light passes through a lens, it is refracted twice: When entering the lens and when emerging from the lens. There is a change 5 in its direction of propagation every time and as both the changes occur in the same sense, the direction of propagation of the emergent ray is different from that of the incident ray.