Linear motion variable inductor and linear motion variable capacitor

In linear motion variable inductor, we have an arm whose movement is same as that of the component, the linear movement of which is to be detected. This arm is connected to a soft-iron core which moves into a coil. The change in inductance of the coil is proportional to the linear movement of the component. When the soft-iron core is moving further, inductance is increased and inductance get reduced when soft-iron core moves out of the coil.

In linear motion variable capacitor, linear motion is converted to a capacitance change. This device consists of two plates in which one is fixed and the other one movable. These two plates form a capacitor. The moving component whose linear movement is to be detected is connected to the movable plate with the help of an arm. The movable plate’s motion is towards fixed plate when the motion of the component is towards the right. Now the capacitance is increased. When the movable plate is moved farther away from the fixed plate, the capacitance is decreased.