Question

are there converging and expanding parts of the slinky?

Answer 1

what is the meaning of slinky

Answer 2

Secure one end of a Slinky to a wall.

Hold the Slinky at one end and stretch it by walking. 

Walk backwards. Now Stop walking. Hold on to one end, bunch up some of the coils in your hand. Then Let go.

It will “sproing” back and forth. There are areas where the Slinky is compressed, and parts where it is expanded like a longitudinal wave.