Crookes Radiometer - Prefix radio- and Suffix -meter

Prefix radio- and Suffix -meter

• The prefix "radio-" in the title originates from the combining form of Latin radius, a ray: here it's referred to electromagnetic radiation.
• A Crookes radiometer, consistent with the suffix "- meter" in its title, can provide a quantitative measurement of electromagnetic radiation intensity.

This can be done, for example, by visual means (e.g., a spinning slotted disk, which functions as a simple stroboscope) without interfering with the measurement itself.

Radiometers are now commonly sold worldwide as a novelty ornament; needing no batteries, but only light to get the vanes to turn. They come in various forms, such as the one pictured, and are often used in science museums to illustrate "radiation pressure" – a scientific principle that they do not in fact demonstrate.