Induction motor Operation & Equivalent circuit

When the stator coils is energized a rotating magnetic field is created.
This rotating magnetic field cuts through the rotor and induces a voltage on the rotor bars.
The voltage on the rotor bars creates its own rotating magnetic field in the rotor.
The rotor magnetic field will try to line up wit the stator magnetic field and will cause the rotor to rotate.
The rotor magnetic field never catches up but follows slightly behind and the difference is known as slip,s.

s is a variable that is always changing. These are not actual resistance you can see and measure in the machine ; they are representations of the  machine. The equivalent circuit is similar to the transformer equivalent circuit but the difference is ( in drawing) is that there is an air gap and the stator and rotor impedance is not combined.