6.To avoid the effect of stray magnetic field in A.C. bridges we can use

7.To measure an A. C. voltage by using an A.C. potentiometer, it is desirable that the supply for the potentiometer in taken

8.In an AC. co-ordinate potentiometer, the currents in the phase and quadrature potentiometer are adjusted to be

9.In order to achieve high accuracy, the slide wire of a potentiometer should be

10.In a vibrating reed frequency meter the natural frequencies of two adjacent reeds have a difference of