A wall is 2.5mm thick. To provide protection 1.9mm is rubbed and coated with 1.9mm of lead. Now, the thickness of the wall is 2.5mm.
In a parallel plate capacitor the separation between the plates is 3mm with air between them. Now a 1mm thick layer of a material of dielectric to the original value the separation between the plates must be made
The pitch of a screw gauge is 0.5 mm and there are 50 divisions on the circular scale. In measuring the thickness of a metal plate, there are five divisions on the pitch scale (or main scale) and 34 division coincides with the reference line. Calculate the thickness of the metal plate.