What is the usage of a solenoid?
It converts electrial energy to a mechanical energy, such as pulling or pushing a lever when a switch is closed.
How does it works?
An electric current in a coil attracts an iron plunger into its centre.
What is Pull and thrust?
Look these words up in your dictionary.
And how do we see the graph: force vs stroke?
One looks at it ???
What is the graph trying to tell us?
The force vs stroke relationship.
You should get hold of a book about basic electricity. If this question was prompted by your school homework your school should have one, else, try your library.
Klaus