An LVDT is a position measuring device whose operation is based on _______. Pleasediscuss your answer.A) Changes in resistanceB) Counting of digital pulsesC) Using a linear capacitor to transform a voltage differentialD) Magnetic coupling of primary and secondary coilsE) Transforming a DC signal to an AC signal

An LVDT, or Linear Variable Differential Transformer, is a type of electromechanical transducer that can convert rectilinear motion of an object to which it is coupled mechanically into a corresponding electrical signal. The operation of an LVDT is based on the principle of magnetic coupling of primary and secondary coils.

Here's a step-by-step explanation:

1. The LVDT consists of a primary coil and two secondary coils wound on a cylindrical former. The secondary coils are connected in series and the primary coil is energized with an AC supply.

2. A movable soft iron core is placed inside the cylindrical former. The position of this core determines the magnetic coupling between the primary and the secondary coils.

3. When the core is in the middle, the voltages induced in the two secondary coils are equal but opposite in phase. Therefore, the net output voltage is zero.

4. When the core moves away from the middle, the coupling with one of the secondary coils increases and with the other decreases. This causes the voltages induced in the secondary coils to become unequal, resulting in a net output voltage.

5. The magnitude of the output voltage is proportional to the displacement of the core, and the phase of the output voltage indicates the direction of the displacement.

So, the correct answer is D) Magnetic coupling of primary and secondary coils.