what is the function of tester
Answers
Inductance testers, better known as non-contact voltage testers, are probably the safest testers around, and they're certainly the easiest to use. They allow you to check for voltage in wires or devices without you having to touch any live parts. The device is like a mini wand with a small tip on the end that senses voltage in such things as electrical wiring, outlets, circuit breakers, lamp cords, light sockets, and switches. You can get a reading simply by sticking the tip of the tester into an outlet slot or even touching the outside of a wire or electrical cable. Sometimes it can pick up voltage without even touching the item.
Inductance testers use a battery to power the device, and most models inform you of voltage present with a red light at the tip of the tester as well as a buzzing sound. They come complete with a handy pocket clip so you can carry it close to your heart and always have it ready for safety purposes.