JNTU B.Tech II TRANSDUCTION OF PHYSICAL VARIABLES Previous Question Paper (September - 2021 - R13)

The method of inherent insensitivity involves designing the physical structure or the material properties of a measuring instrument such that it becomes naturally unresponsive or immune to the effects of interfering and modifying inputs. This is achieved through careful selection of materials and mechanical design rather than through external compensation circuits.

Key approaches include:

• Material Selection: Choosing materials with low temperature coefficients or high stability ensures that environmental changes like ambient temperature fluctuations do not alter the instrument's output.
• Structural Symmetry: Designing the sensor with physical symmetry allows common-mode interfering inputs to cancel each other out. For example, in a differential pressure sensor, if both sensing elements are exposed to the same ambient pressure change, the differential output remains unaffected.
• Negative Feedback: Incorporating high-gain negative feedback loops can make the system's overall transfer function dependent primarily on the feedback elements, which can be chosen for their stability, thereby reducing the sensitivity of the system to variations in the internal components caused by modifying inputs.

A sensor is a device that detects a physical stimulus (such as light, heat, or pressure) and provides a signal, often in the form of a change in a physical property. A transducer is a broader device that converts energy from one form to another, specifically transforming a non-electrical physical quantity into an electrical signal.

The primary difference is that a sensor is the sensing element itself, while a transducer typically includes the sensing element plus the signal conditioning required to produce a usable electrical output.

Sensors are classified as follows: