INTRODUCTION: The radiometer is educational and physical demonstration object that was invented by English physicist Crooks about 100 years ago. Today the Radiometer has become a home decoration or holiday gift.Of course, it can also be a physics teaching tool.HOW DOES IT WORK? The radiometer consists of a glass bulb with a partial vacuum.Inside are four vases which are mounted on a spindle.The vanes rotate when exposed to sunlight,artificial light or infrared radiation.