Correct Answer - Option 3 : Pollution detection
Explanation:
Capacitive Sensors:
- A capacitor consists of a pair of conductors, since no other materials are involved, capacitive sensors are very robust and stable and applicable at high temperatures and in harsh environments.
- The dimensions of capacitive sensors may vary from extremely small, up to very large (several metres).
- The theoretical relation between displacement and capacitance is governed by a simple expression, which in practice can be approximated with high accuracy, resulting in very high linearity.
- Using special constructions, the measurement range of capacitive sensors can be extended almost without limit while maintaining intrinsic accuracy. Moreover, because of the analogue nature of the capacitive principle, the sensors have excellent resolution.
Capacitive Sensors are used in the measurement of:
- Acceleration
- Force
- Torque
- Mass (Level control of Liquids)
- Angular position (Metrology application to measure shape errors)
- Pressure (Small vessel pump control)
Hence, it cannot be used in pollution detection