A sensor is a device which converts physical parameters to some electrical signal. A sensor senses some physical property (such as temperature, speed, presence of object, motion, acceleration) and converts it to some electrical property signal. Given below are topmost sensors that are used in Electrical and Electronics Industry.
A proximity sensor is a non-contact sensor which detects the presence of objects. A proximity sensor uses infrared, ultrasound, inductance, capacitance, or magnetism methods in its working.
The figure below displays an inductive based proximity sensor:
Sensors like these are recommended for the detection of metallic targets. Practically inductive based sensors are used in metal detectors.
NTC thermistor is a negative temperature coefficient resistor: whose resistance decreases with the increase in temperature. The figure below displays an NTC thermistor.
Practically NTC thermistors are used in temperature measurements.
RTD or resistance temperature detector is a positive temperature coefficient device whose resistance increases as temperature increases.
A photoresistor is a passive component with two leads. When light falls on the surface or photoresistor the resistance between its leads diminishes. Photoresistors are used in night lights, street lamps, and solar road studs.
As the name implies, an accelerometer is a sensor which measures the acceleration of a body. The figure below displays an accelerometer sensor by adafruit. Sensors like these can be used in your electronic projects as well as many practical devices.
The voltage or potential difference is one of the basic properties of electrical circuits. A voltage sensor measures the potential difference between any two points in the circuit and provides data in the form of volts. Since voltage is the most basic property of electrical circuits, voltage sensors are found everywhere. They can be found in voltage monitoring panels.
A current sensor measures the flow of current through any wire and provides an output that can be interpreted. Just like the voltage, the electric current is a fundamental property of electric circuits. The ammeter is a practical device which senses the flow of electric current.