Reactance coil 1 is connected into an a -с circuit w ith constant
voltage and frequency. Force F, app lied to armature 2, bends
flat springs 3 and 4, supporting the armature, downward. At
this, armature 2 moves downward, reducing the air gap between
the armature and the core of coil 1 an d, thereby, changing the
current in the coil. This current, indicated by ammeter 5, depends
upon the am o unt armature 2 moves downward. This,
in turn, is proportional to force F.
$4384$SmE,M$