We live in a world of sensors.As in everyday life, you  can find different types of sensors in our offices,car and homes etc. They are used to detect the smoke, adjust the  temperature etc.So we can define sensor as:

“A sensor is a device that  responds to any change in physical phenomena or environmental variables like heat,pressure ,humidity and movement.”

Based on these ,there are two types of electrical sensors:

1. Voltage sensor
2. Current sensor