Transducers are devices that convert physical phenomenons, such as air pressure, light and sounds into an electrical signal. And vice versa. Transducers are very useful when dealing with our environment.

For example, a light detector is a transducer that will convert 'what it sees' into an electrical signal – typically high current or low current.

Transducers come in two forms:

• Input transducer: converts electrical signal (V) to resistance,

i.e. sensors.

• Output transducers: converts electrical signal (V) to another quantity, i.e. loudspeakers.