# Transducer

## What is a Transducer?

A transducer is an electronic device that converts energy from one form to another. The process of converting energy from one form to another is known as transduction.

Some common examples of transducers include loudspeakers, microphones, thermometers and LEDs.

### Why do we need a transducer?

To determine the exact magnitude of physical forces such as temperature and pressure is difficult. But, if these physical forces are converted into an electrical signal, then their values can be easily determined using a meter. The primary function of transducers is to convert a physical force into an electrical signal so that it can be easily handled and transmitted for measurement.

### Advantages of converting a physical quantity into an electrical signal

Here, we have listed the various advantages of converting a physical quantity into an electrical signal:

• Electrical signals are easily transmitted and processed for measurement.
• Electrical signals process less friction error.
• Small power is needed to control the electrical systems.
• Amplification and attenuation of electrical signals are easy.
• The measuring instrument used for measuring the electrical signal is very compact and accurate.

## Parts of Transducer

A transducer consists of the following two important parts:

• Sensing element
• Transduction element

Transducers have other vital parts such as signal processing equipment, amplifiers and power supplies.

### Sensing Element

It is the part of a transducer that responds to the physical sensation. The response of the sensing element depends on the physical phenomenon.

### Transduction Element

The transduction element of the transducer converts the output of the sensing element into an electrical signal. The transduction element is also called the secondary transducer.

## Types of Transducers

There are two types of transducers, as follows:

• Input Transducer
• Output Transducer

### What is an Input Transducer?

An input transducer or a sensor takes in physical energy and converts it into an electrical signal that can be read. A microphone, for example, converts physical sound waves into an electrical signal that can be transferred through wires.

### What is an Output Transducer?

An output transducer, or an actuator, takes in electrical signals and converts them into other forms of energy. A lamp converts electricity into light and a motor, on the other hand, converts electricity into motion.

### Factors to consider while selecting a transducer

• Transducers should have high input impedance and low output impedance to avoid the loading effect.
• A transducer should be highly sensitive to desired signals and insensitive to unwanted signals.
• Transducers should be able to work in corrosive environments.

## Transducer Efficiency

Transducer efficiency is defined as the ratio of output power in the desired form to the total power input. Mathematically, the ratio is represented as follows:

$$\begin{array}{l}E=\frac{Q}{P}\end{array}$$

P represents the input in the above ratio, and Q represents the power output in the desired form. The efficiency of the transducer always falls between 0 and 1.

No transducer is 100% efficient; some power is always lost in the conversion process. This loss is manifested in the form of heat. In incandescent lamps of certain wattage, only a few watts are transformed into visible light. Most of the power is dissipated as heat. Due to this, an incandescent lamp is a bad transducer in terms of efficiency.

## Applications of Transducer

• A transducer measures load on the engines
• They are used to detect the movement of muscles; this process is known as acceleromyograph.
• Transducers are used in an ultrasound machine.
• The transducers in a speaker convert electrical signals into acoustic sound.
• A transducer is used in the antenna to convert electromagnetic waves into electrical signal.

## Difference Between a Transducer and a Sensor

A sensor is a device that measures a physical quantity. For example, in a mercury thermometer, the mercury simply expands when the temperature rises to give a reading for the user. Here there are no electrical inferences or changes. On the other hand, a transducer, measures similar quantities as a sensor but the signal in a transducer is converted from one form to another. This is the reason why transducers are also referred to as energy converters.

 Transducers Sensors It converts energy from one form to another. It senses physical quantities and converts it into a readable form. Cable extension transducer, linear transducer and microphones are some examples of transducers. Thermistors, pressure switches and motion sensors are some examples of sensors.

## Frequently Asked Questions on Transducer

### What is the difference between a sensor and a transducer?

Both sensors and transducers sense change within the environment they are surrounded by. The difference lies in the output of each device. In a sensor, the output is in the same form as the input, but the input is converted into an electrical signal in a transducer.

### Why is a transducer important?

Transducers transform physical quantity into an electrical signal. Transducers are essential in detecting and quantifying such signals (pressure, air humidity, temperature, etc.)

### Give an example of a transducer.

Any device that converts energy from one form to another is known as a transducer. A loudspeaker is one of the common examples of a transducer. A speaker converts an electrical signal to sound waves.

### Is a thermometer a sensor or a transducer?

A thermometer is both a transducer and a sensor.

### Where is a transducer used?

Transducers are commonly used in applications that require automation and measurement. In

such applications, the electrical signals are converted to and from other physical quantities.

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