The Crookes radiometer (also known as a light mill) consists of an airtight glass bulb containing a partial vacuum, with a set of vanes which are mounted on a spindle inside.
The reason for the rotation was a cause of much scientific debate in the ten years following the invention of the device, but in 1879 the currently accepted explanation for the rotation was published. Today the device is mainly used in physics education as a demonstration of a heat engine run by light energy.
Crookes Radiometer apparatus mounted on a sturdy plastic molded base. Comprised on an evacuated glass bulb with black and white veins.Comprised on an evacuated glass bulb with black and white veins. Each vein has a blackened side and the reverse side is bright. 70mm diameter at the widest point, containing a fine pivot which supports four light weight metal arms.