Sensing element in the thermometer must provide large change in resistance.

The sensing element in a thermometer is responsible for converting the temperature change into a corresponding change in resistance. This change in resistance is then measured and used to determine the temperature. The sensing element is typically made of a material with a known and predictable relationship between temperature and resistance, such as a thermistor or a resistance temperature detector (RTD).

Importance of a large change in resistance:

A large change in resistance is important for accurate temperature measurement because it allows for better resolution and sensitivity. The greater the change in resistance for a given change in temperature, the more precise the measurement can be. This is particularly important when measuring small temperature changes or when high accuracy is required.

Reasons for a large change in resistance:

1. Linear response: The sensing element should provide a linear relationship between temperature and resistance. This means that as the temperature increases or decreases, the resistance should change in a proportional manner. A linear response allows for more accurate temperature readings and easier calibration.

2. Wide operating range: The sensing element should have a wide operating range, meaning it can accurately measure a wide range of temperatures. This ensures that the thermometer can be used in various applications and environments without compromising accuracy.

3. Stable and repeatable: The sensing element should exhibit stable and repeatable resistance-temperature characteristics over time. This means that the resistance change should not drift or vary significantly with time or usage. A stable and repeatable sensing element ensures consistent and reliable temperature measurements.

4. High sensitivity: The sensing element should have a high sensitivity to temperature changes. This means that even small temperature variations should result in significant resistance changes. High sensitivity allows for precise temperature measurements and better detection of subtle temperature changes.

By providing a large change in resistance, the sensing element in a thermometer can ensure accurate and reliable temperature measurements. This is crucial in various industries and applications where temperature control and monitoring are essential, such as in healthcare, environmental monitoring, and industrial processes.