How many type of smoking?

Answer 1

There are basically two types of smoke detector;

one type measures the opacity of the air to literally "see" if there is smoke.

The other type tests for ionization that occurs when there is a fire. That type smoke detector uses a small radioactive chip to determine if freshly ionized smoke is present. It's a far more accurate means of determining the presence of fire and associated hazardous smoke.

Many smoke detectors use a combination of both detectors.

A separate type of detector is the carbon monoxide detector, which senses the presence of harmful carbon monoxide in the air. Most will even indicate the percentage of carbon monoxide. Note that carbon monoxide is typically present when a furnace or other heating device malfunctions.