A screw gauge of pitch 1mm has a circular scale divided into 100 divisions and has no zero error.  When the diameter of a wire is measured using this screw gauge, the main scale reading is 1 mm and the 47^th circular division coincides with the main scale.  The length of the wire is given as 5.6 cm.  The curved surface area of the wire up to the correct significant figures is

The distance moved by the screw of a screw gauge is $2 \mathrm{mm}$ in four rotations and there are 50 divisions on its cap. When nothing is put between its jaws, 20th division of circular scale coincides with reference line and zero of linear scale is hidden from circular scale when two jaws touch each other or zero of circular scale is lying above the reference line. When plate is placed between the jaws, main scale reads 2 divisions and circular scale reads 20 divisions. Thickness of plate is