Which of the following transducers operates on the principle of variable capacitance? 

Explanation:

Capacitive Displacement Sensor

• A capacitive displacement sensor is a type of transducer that measures changes in position or displacement by detecting variations in capacitance. The basic principle of operation involves a capacitor with a movable plate, where changes in the position of the plate affect the capacitance of the system.

Working Principle:

• The capacitive displacement sensor operates based on the formula for the capacitance of a parallel-plate capacitor:

C = (ε × A) / d

Where:

• C is the capacitance
• ε is the permittivity of the dielectric material between the plates
• A is the area of the plates
• d is the distance between the plates

In a capacitive displacement sensor, as the distance (d) between the plates changes due to the displacement of the movable plate, the capacitance (C) also changes. This change in capacitance is measured and converted into a displacement reading.

Advantages:

• High sensitivity to small changes in displacement
• Non-contact measurement, reducing wear and tear
• High resolution and accuracy

Disadvantages:

• Sensitivity to environmental factors such as temperature and humidity
• Limited measurement range
• Requires careful calibration to ensure accurate readings

Applications: Capacitive displacement sensors are widely used in precision engineering, semiconductor manufacturing, and any application requiring high-accuracy position measurements, such as in microscopy and nanotechnology.