What are Transducers?
We have seen that there are two methods of measurement of any physical quantity: the direct method and the indirect method. In the direct method any physical quantity like length, mass, etc are measured directly by some instruments like the measuring tape, weighing scale etc. In the indirect method of measurements some transducing devise, called transducer, is used, which is coupled to a chain of the connecting apparatus that forms the part of the measuring system. In this system the quantity which is to be measured (input) is converted into some other measurable quantity (output) by the transducer.
Transducers are the mechanical, electrical, electronic, or electromechanical devices that convert one form of the energy or the property that cannot be measured directly into the other form of energy or property that can be measured easily. The signal given to the transducers is called as input, this is the parameter that is to be measured but cannot be measured directly. The signal obtained from the transducer is called as output, which can be measured easily.
The transducer selected for the measuring system is such that the output obtained is proportional to the input. Since the output can be measured easily by the available instruments, the scale can be calibrated between the values of the output and the input. From this calibration, for all the values of the output the input value i.e. the parameter or physical quantity to be measured can be obtained easily.
The transducers are used for various applications, but here we are considering transducers used for the measurement of the physical quantities like temperature, pressure, flow etc.