The distance moved by the screw of a screw gauge is 2 mm in four...

The distance moved by the screw of a screw gauge is $2$ mm in four rotations and there are $50$ divisions on its cap. When nothing is put between its jaws, ${30}^{th}$ division of circular scale coincides with the reference line, with zero of circular scale lying above the reference line. When a plate is placed between the jaws, the main scale reads $2$ divisions and the circular scale reads $20$ divisions. The thickness of the plate is