Characteristics of Sensors
The performance of a sensor depends on several important characteristics. These characteristics determine how accurately and efficiently a sensor measures physical quantities. Understanding these properties is essential for selecting the right sensor in an IoT system.
Exam Tip:
Characteristics of Sensors is one of the most frequently asked topics in RGPV examinations.
1. Accuracy
Accuracy is the degree to which the measured value of a sensor matches the actual value of the physical quantity being measured.
Higher accuracy means the sensor produces results that are very close to the true value.
Example:
If the actual temperature is 30°C and the sensor displays 29.9°C, then the sensor has high accuracy.
2. Precision
Precision refers to the ability of a sensor to produce the same output repeatedly when measuring the same quantity under identical conditions.
A sensor may be precise but not accurate if it repeatedly produces the same incorrect reading.
3. Resolution
Resolution is the smallest change in the input that can be detected by a sensor.
Higher resolution enables the sensor to detect very small variations.
Example:
A temperature sensor that detects a change of 0.1°C has better resolution than one that detects only 1°C.
4. Sensitivity
Sensitivity is the ratio of change in sensor output to the change in input quantity.
A highly sensitive sensor responds quickly even to small changes.
5. Linearity
Linearity indicates how closely the output of a sensor follows a straight-line relationship with the input.
Better linearity results in easier calibration and more accurate measurements.
6. Repeatability
Repeatability is the ability of a sensor to produce the same output for repeated measurements under the same conditions.
Sensors with good repeatability are highly reliable in industrial and IoT applications.
7. Error
Error is the difference between the measured value and the actual value.
Error may occur due to environmental conditions, improper calibration, noise, or sensor aging.
8. Response Time
Response time is the time taken by a sensor to respond to a sudden change in the measured quantity.
Smaller response time is preferred for real-time IoT applications.
9. Dead Band
Dead Band is the range of input values over which the sensor produces no change in output.
A smaller dead band improves measurement quality.
10. Impedance
Impedance represents the opposition offered by a sensor to the flow of electrical current.
Proper impedance matching improves signal quality and reduces measurement errors.
11. Backlash
Backlash is the difference in output obtained when the input is approached from opposite directions.
Mechanical sensors often exhibit backlash because of friction and looseness.
Summary Table
| Characteristic |
Description |
| Accuracy |
Closeness to true value |
| Precision |
Repeatability of measurements |
| Resolution |
Smallest detectable change |
| Sensitivity |
Output change per unit input |
| Linearity |
Straight-line response |
| Repeatability |
Produces same output repeatedly |
| Error |
Difference from true value |
| Response Time |
Time required to respond |
| Dead Band |
No output for small input changes |
| Impedance |
Opposition to current flow |
| Backlash |
Difference due to reverse motion |