Transducers are the devices that convert one form of physical energy into another form of energy. The physical energies can be in any form temperature, displacement, electromagnetic, thermal, and many others.
Transducers are used in our day to day life and we are well surrounded by them. For example, a light bulb is a transducer that converts electrical energy into light energy. Our ears and brain also work as a transducer, ear receives the pressure waves and converts them into electrical impulses that our brain perceives as sound.
Image by Colin Behrens from Pixabay 
Common examples of transducers include microphones, loudspeakers, thermometers, and antennas, and many more.
Any devices can be judged on their efficiency and so does the transducers. Its efficiency is the ratio of output power to the total input power. For instance, F is the input power and P is the output power, then the efficiency formula is given by E=p/F. The efficiency ratio is between 0 and 1. A device cannot work with 1005 efficiency, it always has some losses in the form of heat.
Types of transducers
There are different types of transducers that work to change specific energy into electrical energy. Therefore, they are broadly categorized in these categories.
Principle of operation
- Mutual Induction
- Chemical
- Photovoltaic ( e.g. a solar cell )
- Piezoelectric.
Measuring the quantities
- Temperature transducers (e.g. a thermocouple)
- Pressure transducers (e.g. a diaphragm)
- Displacement transducers (e.g. LVDT)
Based External Power Source
- Active Transducer
It works on the principle of conversion of energy. They do not need any power sources to work. They give output proportional to the input. The common example of an active transducer is a thermocouple and piezoelectric accelerometers.
- Passive Transducers
Contrarily to active transducers, it requires a power source to work. They give output in the form of change in the resistance, capacitance, or other electrical parameters. Its common example is photocell.
Working of transducers
The simplest example to understand the working of a transducer can be the mic of telephones. The mic converts the sound waves into electrical signals. The system amplifies electrical signals sends to another transducer which converts it into sound waves.
Another common example of a transducer is a fish finder device. It uses an echo sounder system which has an ultrasound transducer in it. The echo sounder changes the electrical signals into the sound waves and sends off in the water. These waves travel through the waters and strike different objects at different locations. After striking different objects these waves reflect towards the echo-sounder system. Here, now echo-sounder converts the sound waves into the electrical signal. The echo-sounder systems calculate the time difference between the waves sent away and received later. This calculation provides the exact location of the object in the water.
By looking at so many examples, we can say the transducers certainly have wide application in almost all the devices. Mention the example of the transducers if you find any nearby you.
